Re: [Tutor] sort() method and non-ASCII

[eryk sun]

On Sun, Feb 5, 2017 at 3:52 AM, boB Stepp  wrote:
> Does the list sort() method (and other sort methods in Python) just go
> by the hex value assigned to each symbol to determine sort order in
> whichever Unicode encoding chart is being implemented?

list.sort uses a less-than comparison. What you really want to know is
how Python compares strings. They're compared by ordinal at
corresponding indexes, i.e. ord(s1[i]) vs ord(s2[i]) for i less than
min(len(s1), len(s2)).

This gets a bit interesting when you're comparing characters that have
composed and decomposed Unicode forms, i.e. a single code vs multiple
combining codes. For example:

>>> s1 = '\xc7'
>>> s2 = 'C' + '\u0327'
>>> print(s1, s2)
Ç Ç
>>> s2 < s1
True

where U+0327 is a combining cedilla. As characters, s1 and s2 are the
same. However, codewise s2 is less than s1 because 0x43 ("C") is less
than 0xc7 ("Ç"). In this case you can first normalize the strings to
either composed or decomposed form [1]. For example:

>>> strings = ['\xc7', 'C\u0327', 'D']
>>> sorted(strings)
['Ç', 'D', 'Ç']

>>> norm_nfc = functools.partial(unicodedata.normalize, 'NFC')
>>> sorted(strings, key=norm_nfc)
['D', 'Ç', 'Ç']

[1]: https://en.wikipedia.org/wiki/Unicode_equivalence#Normal_forms
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Re: [Tutor] Function annotations

[boB Stepp]

On Sat, Feb 4, 2017 at 9:23 PM, Steven D'Aprano  wrote:
> On Sat, Feb 04, 2017 at 08:50:00PM -0600, boB Stepp wrote:

>> Of course, these are
>> apparently optional.  I now wonder if I should be endeavoring to add
>> these to my code?
>
> Do you run a linter? If not, there doesn't seem much point in adding
> annotations.

To date I have avoided adding a linter to vim/gvim as I believe I get
more educational benefit from making and correcting mistakes that a
linter would catch.  But I have it in the back of mind if I ever reach
a relative point of Python comfort to implement linting capabilities.
Are the people making linters implementing checking function
annotations?  Or is this something only gradually being adopted?

Steve, are you making use of function annotations?  If yes, are you
finding them worth the extra effort?

Cheers!
boB
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[Tutor] sort() method and non-ASCII

[boB Stepp]

Does the list sort() method (and other sort methods in Python) just go
by the hex value assigned to each symbol to determine sort order in
whichever Unicode encoding chart is being implemented?  If yes, then
my expectation would be that the French "á" would come after the "z"
character.  I am not ready to get into the guts of Unicode.  I am
quite happy now to leave Python 3 at its default UTF-8 and strictly
type in the ASCII subset of UTF-8.  But I know I will eventually have
to get into this, so I thought I would ask about sorting so I don't
get any evil surprises with some text file I might have to manipulate
in the future.

Thanks!

-- 
boB
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Re: [Tutor] Function annotations

[Steven D'Aprano]

On Sat, Feb 04, 2017 at 08:50:00PM -0600, boB Stepp wrote:
> I just finished looking at
> https://docs.python.org/3/tutorial/controlflow.html#function-annotations
> and skimming through PEP 484--Type Hints
> (https://www.python.org/dev/peps/pep-0484/).  My initial impression is
> that the purpose of function annotations is to enable static code
> analysis tools like linters to be more effective.

That's exactly what they're for.

> Aesthetically, to
> my eye it makes the function definition line more cluttered looking
> and more difficult to interpret at a glance.

Obviously they take up more room, but they also provide more 
information: the intended type of the argument,



> Of course, these are
> apparently optional.  I now wonder if I should be endeavoring to add
> these to my code?

Do you run a linter? If not, there doesn't seem much point in adding 
annotations.


> It is not clear to me how to implement function annotations in all
> instances.  Starting with a rather useless function:
> 
> def prt_stupid_msg():
> print('Duh!')
> 
> This takes no arguments and returns None.  While this particular
> function is rather useless, many others of some utility may take no
> arguments and return None.  How should these types of functions be
> annotated?

Since it take no arguments, you cannot annotate the arguments it 
doesn't have.

You could annotate the return value:

def prt_stupid_msg() -> None: 
print('Duh!')


but that's unlikely to be useful. I wouldn't bother.



> What about:
> 
> def print_stuff(stuff):
> print(stuff)
> 
> Should this be annotated as:
> 
> def print_stuff(stuff: Any) -> None:
> 
> ?


Probably not. If you don't annotate the function, the linter should just 
assume it takes anything as argument.


> What about a function from the tutorial:
> 
> def make_incrementor(n):
> return lambda x: x + n
> 
> n might always be an int or might always be a float or might be
> either, depending on the author's intent.  Therefore, how should n be
> annotated?  In accordance with the author's intentions?

Of course.

> And what
> about the case where n is sometimes an integer and sometimes a float?

That's a Union of two types. Think of Union as meaning "this OR that".


> And the return in this instance is a function.  Should the return be
> annotated "function"?

from typing import Union
from types import FunctionType

def make_incrementor(n: Union[int, float]) -> FunctionType:
return lambda x: x + n



> And what about functions that return different types depending on
> conditional statements?

Probably a bad design...


> How would these varying return types be annotated?  Say:
> 
> def return_typed_value(desired_type, value):
> if desired_type = 'string':
> return str(value)
> elif desired_type = 'integer':
> return int(value)
> elif desired_type = 'float':
> return float(value)
> 
> What should I do with this?

Redesign it.

def return_typed_value(
desired_type: str, value: Any) -> Union[str, int, float]:
...



> As written "desired_type" will always be
> a string, but "value" will be potentially several different types.

If you want to restrict the type of `value` depending on the value of 
`desired_type`, you cannot expect the compiler or linter or type-checker 
to do this at compile time. In general, it doesn't know what the value 
of `desired_type` is, so it can't tell whether the type of `value` is 
valid or not.

You would have to use a *dynamic* type check, rather than static:

def return_typed_value(desired_type, value):
if desired_type == 'string':
if isinstance(value, (int, float)):
return str(value)
elif desired_type == 'integer':
if isinstance(value, (float, str)):
return int(value)
elif desired_type == 'float':
if isinstance(value, (int, str)):
return float(value)
raise TypeError



When your type checking rules become this intricate, it's probably a bad 
idea.


-- 
Steve
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[Tutor] Function annotations

[boB Stepp]

I just finished looking at
https://docs.python.org/3/tutorial/controlflow.html#function-annotations
and skimming through PEP 484--Type Hints
(https://www.python.org/dev/peps/pep-0484/).  My initial impression is
that the purpose of function annotations is to enable static code
analysis tools like linters to be more effective.  Aesthetically, to
my eye it makes the function definition line more cluttered looking
and more difficult to interpret at a glance.  Of course, these are
apparently optional.  I now wonder if I should be endeavoring to add
these to my code?

It is not clear to me how to implement function annotations in all
instances.  Starting with a rather useless function:

def prt_stupid_msg():
print('Duh!')

This takes no arguments and returns None.  While this particular
function is rather useless, many others of some utility may take no
arguments and return None.  How should these types of functions be
annotated?

What about:

def print_stuff(stuff):
print(stuff)

Should this be annotated as:

def print_stuff(stuff: Any) -> None:

?

What about a function from the tutorial:

def make_incrementor(n):
return lambda x: x + n

n might always be an int or might always be a float or might be
either, depending on the author's intent.  Therefore, how should n be
annotated?  In accordance with the author's intentions?  And what
about the case where n is sometimes an integer and sometimes a float?
And the return in this instance is a function.  Should the return be
annotated "function"?

And what about functions that return different types depending on
conditional statements?  How would these varying return types be
annotated?  Say:

def return_typed_value(desired_type, value):
if desired_type = 'string':
return str(value)
elif desired_type = 'integer':
return int(value)
elif desired_type = 'float':
return float(value)

What should I do with this?  As written "desired_type" will always be
a string, but "value" will be potentially several different types.
And the return value can be one of three types (Assuming no errors
occur as no exception handling is being done as written.).  What to do
about that?

I have more questions, but these will do for a start.  Just the long
PEP 484 document has tons of meat in it to consider, most of which is
dealing with aspects of Python I have not gotten to studying yet!


-- 
boB
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Re: [Tutor] Syntax error while attempting to type in multiline statements in the interactive interpreter

[boB Stepp]

I'm beginning to believe I am being incredibly dense today ...

On Sat, Feb 4, 2017 at 6:16 PM, Ben Finney  wrote:
> boB Stepp  writes:
>
>> But would it not be more consistent to assume the user knows what he
>> is doing based on the new (lack of) indentation being used, accept
>> that a new section of code outside of the for loop is being typed in,
>> and wait for the blank line before executing everything typed in?
>
> That's not the purpose of the REPL. It is to Read (one statement),
> Evaluate the statement, Print the result, and Loop.
>
> You're wanting a different behaviour: wait until all the input has been
> read, then evaluate it all.

Ben, I read your answer, did some Googling on REPL, seemed satisfied,
and consigned this thread of emails to the trash bin, believing it was
all settled in my mind.  But then I got to wondering again ...

As already mentioned the interactive interpreter handles multiline
statements.  In the case of defining a function, the interpreter
allows quite complex, nested code to be entered, only ending the input
of code process when that blank line occurs in proper context.  By
this I mean that quotes have been properly closed, all parens matched,
etc.

But it seems to me on further thought that both REPL and what seems
most consistent to me, "...wait until all the input has been read,
then evaluate it all..." amounts to the same thing in the case of
entering function definitions into the interpreter.  The interpreter
cannot know that the user has finished inputting code until it
encounters that finalizing blank line.  After all I can have in my
function many for loops followed by unindented print functions in
seeming as much complexity as I can bear to type in accurately.  This
is giving exactly the consistent behavior that I would expect.  But if
instead of starting with a for loop inside a function with following
unindented other statements I instead start with *exactly the same
sequence of statements* but without "def ...:", then I get a syntax
error.  I am not trying to be deliberately argumentative, but I do not
see why the two cases are treated differently when the entered code is
exactly the same between the two with the sole exception of one has an
enclosing function definition line the other code does not.  I am
continuing to scratch my evermore balding head on this one!  But it is
not a big deal, and I do not want to blow things out of proportion.

More practically, I wonder if it is all as simple as not having to hit
the enter key twice for true one-liner statements.  Such lines can
truly be handled one line at a time per REPL.  If I had things "my
way", then that would make the more common situation of true
one-line-at-a-time read-evaluate-print-loop more cumbersome.

-- 
boB
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Re: [Tutor] Syntax error while attempting to type in multiline statements in the interactive interpreter

[Ben Finney]

boB Stepp  writes:

> But would it not be more consistent to assume the user knows what he
> is doing based on the new (lack of) indentation being used, accept
> that a new section of code outside of the for loop is being typed in,
> and wait for the blank line before executing everything typed in?

That's not the purpose of the REPL. It is to Read (one statement),
Evaluate the statement, Print the result, and Loop.

You're wanting a different behaviour: wait until all the input has been
read, then evaluate it all.

If that's what you want: just write it all into a text file, and execute
that.

-- 
 \ “Nature is trying very hard to make us succeed, but nature does |
  `\   not depend on us. We are not the only experiment.” —Richard |
_o__)   Buckminster Fuller, 1978-04-30 |
Ben Finney

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Re: [Tutor] Syntax error while attempting to type in multiline statements in the interactive interpreter

[boB Stepp]

On Sat, Feb 4, 2017 at 5:44 PM, Alan Gauld via Tutor  wrote:
> On 04/02/17 22:56, boB Stepp wrote:
>> On Sat, Feb 4, 2017 at 4:40 PM, David  wrote:
>>> On 5 February 2017 at 09:02, boB Stepp  wrote:
 py3: a
 ['Mary', 'had', 'a', 'little', 'lamb', 'break']
 py3: for w in a:
 ... print(w)
 ... print('Huh?')
   File "", line 3
 print('Huh?')
 ^
 SyntaxError: invalid syntax

 I don't understand why this throws a SyntaxError.  If I wrap
 essentially the same code into a function it works:
>
> Because you never completed the for loop. The interactive
> interpreter tries to exercise each Python statement as it
> goes but it cannot exercise the loop until it sees the end
> of the block. Your second print statement is outside the
> block but the block has not yet been executed so it sees
> an error.

But would it not be more consistent to assume the user knows what he
is doing based on the new (lack of) indentation being used, accept
that a new section of code outside of the for loop is being typed in,
and wait for the blank line before executing everything typed in?

>
> Alternatively if you put your code inside a function
> definition it will understand it because it interprets
> the full definition. Then when you call the function
> it executes it as a whole. There is no discrepency in
> what the interpreter is trying to interpret. But when
> you do it at the top level  the interpreter is still
> waiting for the end of the loop.

Again, the interpreter is waiting for that blank line before deciding
the function definition is complete.  Why cannot this be the key
criteria for the for loop with additional code being added, wait for
the blank line to be entered, and then execute the whole shebang?  To
me, this seems to be more consistent behavior.

> Does that help?

It confirms what I was concluding.  This is what happens when I have
some extra time on my hand, decide to carefully scrutinize the
official Python 3 tutorial, and then think, wonder and play around in
the interpreter.  ~(:>))


-- 
boB
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Re: [Tutor] Syntax error while attempting to type in multiline statements in the interactive interpreter

[Alan Gauld via Tutor]

On 04/02/17 22:56, boB Stepp wrote:
> On Sat, Feb 4, 2017 at 4:40 PM, David  wrote:
>> On 5 February 2017 at 09:02, boB Stepp  wrote:
>>> py3: a
>>> ['Mary', 'had', 'a', 'little', 'lamb', 'break']
>>> py3: for w in a:
>>> ... print(w)
>>> ... print('Huh?')
>>>   File "", line 3
>>> print('Huh?')
>>> ^
>>> SyntaxError: invalid syntax
>>>
>>> I don't understand why this throws a SyntaxError.  If I wrap
>>> essentially the same code into a function it works:

Because you never completed the for loop. The interactive
interpreter tries to exercise each Python statement as it
goes but it cannot exercise the loop until it sees the end
of the block. Your second print statement is outside the
block but the block has not yet been executed so it sees
an error.

If you put a blank line it will work OK.

Alternatively if you put your code inside a function
definition it will understand it because it interprets
the full definition. Then when you call the function
it executes it as a whole. There is no discrepency in
what the interpreter is trying to interpret. But when
you do it at the top level  the interpreter is still
waiting for the end of the loop.

Does that help?

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos


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Re: [Tutor] Syntax error while attempting to type in multiline statements in the interactive interpreter

[David]

On 5 February 2017 at 09:56, boB Stepp  wrote:
> On Sat, Feb 4, 2017 at 4:40 PM, David  wrote:
>>>
>>> I don't understand why this throws a SyntaxError.  If I wrap
>>> essentially the same code into a function it works:
>>
>> From [1]: "When a compound statement is entered interactively, it must
>> be followed by a blank line to indicate completion (since the parser
>> cannot guess when you have typed the last line). Note that each line
>> within a basic block must be indented by the same amount."
>>
>> Does that help?
>
> Not really.  I do not understand why I can define a function in the
> interactive interpreter and nest (apparently) any number of for loops,
> if-elif-else constructs, etc., and as long as I get the indentation of
> each block correct, it will accept it.  But apparently if I start off
> with something which is by definition multiline like typing in a for
> loop, I cannot continue the multiline statements with something
> outside the for loop even if the indentation indicates that the
> following statement is not part of the for loop above.  I can accept
> this, but I do not understand why this can't be parsed correctly by
> the interpreter solely based on the indentation and lack of
> indentation being used.

I am guessing it is because the interpreter implements only single
level of auto-indent, for every top-level compound statement, and it
requires that to be terminated with one blank line.

It appears that all extra indenting must be done manually.

I could be wrong, as I would not work this way. Instead I would use an
editor to create the function, and then import it to create the desired
initial state which could then be explored interactively.

I just tried to give you a quick response. Maybe someone else will
give you a more authoritative answer, if there is one.
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Re: [Tutor] Syntax error while attempting to type in multiline statements in the interactive interpreter

[boB Stepp]

On Sat, Feb 4, 2017 at 4:40 PM, David  wrote:
> On 5 February 2017 at 09:02, boB Stepp  wrote:
>> py3: a
>> ['Mary', 'had', 'a', 'little', 'lamb', 'break']
>> py3: for w in a:
>> ... print(w)
>> ... print('Huh?')
>>   File "", line 3
>> print('Huh?')
>> ^
>> SyntaxError: invalid syntax
>>
>> I don't understand why this throws a SyntaxError.  If I wrap
>> essentially the same code into a function it works:
>
> From [1]: "When a compound statement is entered interactively, it must
> be followed by a blank line to indicate completion (since the parser
> cannot guess when you have typed the last line). Note that each line
> within a basic block must be indented by the same amount."
>
> Does that help?

Not really.  I do not understand why I can define a function in the
interactive interpreter and nest (apparently) any number of for loops,
if-elif-else constructs, etc., and as long as I get the indentation of
each block correct, it will accept it.  But apparently if I start off
with something which is by definition multiline like typing in a for
loop, I cannot continue the multiline statements with something
outside the for loop even if the indentation indicates that the
following statement is not part of the for loop above.  I can accept
this, but I do not understand why this can't be parsed correctly by
the interpreter solely based on the indentation and lack of
indentation being used.

C'est la vie Python!



-- 
boB
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Re: [Tutor] Syntax error while attempting to type in multiline statements in the interactive interpreter

[David]

On 5 February 2017 at 09:02, boB Stepp  wrote:
> py3: a
> ['Mary', 'had', 'a', 'little', 'lamb', 'break']
> py3: for w in a:
> ... print(w)
> ... print('Huh?')
>   File "", line 3
> print('Huh?')
> ^
> SyntaxError: invalid syntax
>
> I don't understand why this throws a SyntaxError.  If I wrap
> essentially the same code into a function it works:

>From [1]: "When a compound statement is entered interactively, it must
be followed by a blank line to indicate completion (since the parser
cannot guess when you have typed the last line). Note that each line
within a basic block must be indented by the same amount."

Does that help?

[1] https://docs.python.org/3/tutorial/introduction.html
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[Tutor] Syntax error while attempting to type in multiline statements in the interactive interpreter

[boB Stepp]

py3: a
['Mary', 'had', 'a', 'little', 'lamb', 'break']
py3: for w in a:
... print(w)
... print('Huh?')
  File "", line 3
print('Huh?')
^
SyntaxError: invalid syntax

I don't understand why this throws a SyntaxError.  If I wrap
essentially the same code into a function it works:

py3: def print_list(a_list):
... for item in a_list:
... print(item)
... print('Huh?')
...
py3: print_list(a)
Mary
had
a
little
lamb
break

What am I not understanding here?

-- 
boB
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Re: [Tutor] Copy/Paste in Tkinter

[Pooja Bhalode]

Hi Alan,

Thank you so much for guiding me towards this. I am new to tkinter hence
not aware of all these features.
I am trying to find some simple examples, of how to use copy/paste/cut. I
do not have a text box, but a GUI similar to a word editor. I was wondering
if you could direct me towards or show me towards some simple examples of
the same, so that it would be easier to understand. I was learning from
youtube videos about this.
It would be a huge help. Thank you so much

Pooja

On Sat, Feb 4, 2017 at 5:32 AM, Alan Gauld via Tutor 
wrote:

> On 04/02/17 00:24, Pooja Bhalode wrote:
>
> > I am trying to write a simple Tkinter code in Python in order to
> > demonstrate select/copy/paste/cut functionalities using keyboard keys and
> > menu options.
>
> You are going a fairly long winded way about it.
> Rather than generating events use the Text/Entry
> widget methods directly.
>
> Check the documentation for the following methods:
>
> Text.get()   # copy
> Text.selection_get(...) # copy a selection
> Text.delete(...)  # cut
> Text.insert(...)  # paste
>
> To control selections look at the tag methods,
> but that is more complex.
>
> > def show_menu(e):
> > w = e.widget
> > # the_menu.entryconfigure("Select",command=lambda:
> > w.event_generate("<>"))
> > the_menu.entryconfigure("Cut",command=lambda:
> w.event_generate("<>"))
> > the_menu.entryconfigure("Copy",command=lambda:
> w.event_generate("<>"))
> > the_menu.entryconfigure("Paste",command=lambda:
>
> These should be in the create function. You don't need
> to configure the command every time you show the menu.
>
> > w.event_generate("<>"))
> > the_menu.tk.call("tk_popup", the_menu, e.x_root, e.y_root)
>
> You should only need to call the tk.call() method very,
> very rarely, there is usually a more direct way to do things.
>
> > root = Tkinter.Tk()
> > make_menu(root)
> >
> > e1 = Tkinter.Entry(); e1.pack()
> > e2 = Tkinter.Entry(); e2.pack()
>
> Shouldn't these Entries have a parent?
>
> --
> Alan G
> Author of the Learn to Program web site
> http://www.alan-g.me.uk/
> http://www.amazon.com/author/alan_gauld
> Follow my photo-blog on Flickr at:
> http://www.flickr.com/photos/alangauldphotos
>
>
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Re: [Tutor] Using venv

[Juan C.]

On Fri, Jan 27, 2017 at 7:47 PM, Jim  wrote:
>
> [...] This question seems a little dumb and maybe I am being a little dense, 
> but then what?

Imagine that you are working on 5 different Python projects, each
using different packages with different versions. We can break this
down in two situations:

1. No virtualenv
1.a. You only have one Lib/site-packages to hold all your packages
1.b. Project A uses package-abc 1.2 while Project B uses package-abc 1.5
1.c. You go to work on Project B using package-abc 1.5, but later on
you have to do some changes on Project A so you must downgrade
package-abc to 1.2. Too bad you have to fix some bugs on Project B the
next day, need to update package-abc back to 1.5

2. Virtualenv
2.a. You had multiple virtualenvs, each of them having their own
Lib/site-packages
2.b. Project A uses one virtualenv with package-abc 1.2 while Project
B uses another virtualenv with package-abc 1.5
2.c. You go to work on Project B using package-abc 1.5, so you
activate its venv, but later on you have to do some changes on Project
A so you activate the other venv. Too bad you have to fix some bugs on
Project B the next day, activate Project B venv.

It's a simple command to activate/deactivate a venv vs all the work
you have to do when not using venv.
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Re: [Tutor] Copy/Paste in Tkinter

[Alan Gauld via Tutor]

On 04/02/17 16:09, Pooja Bhalode wrote:

> I do not have a text box, but a GUI similar to a word editor.

That sounds like a text box to me!?
What are you using to enter the text if not a Text widget?

> I was learning from youtube videos about this.

You can start with the GUI topic in my tutorial(see .sig)

It contains links to a couple of other Tkinter tutorials on
the web. The Python.org Tkinter page also has links.
All of these cover text processing to some degree.

Finally there are a couple of books to consider:
1) Python & Tkinter by Grayson on Manning Press
2) Programming Python 4th edition which has about
400 pages of Tkinter material, including a text editor.

3) And I can't resist a plug for my recent book "Python Projects"
which has a more modest 30 page intro on Tkinter, but
includes coverage of the get, delete and insert text methods,
as well as how to set fonts and build menus :-)

You may be able to get these via your local public/college library.

-- 

Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos

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Re: [Tutor] Tkinter Copy/Paste/Cut functionalities

[Alan Gauld via Tutor]

On 04/02/17 02:34, Pooja Bhalode wrote:

> I came across some snippets of the code to do this but using a self class.

I'm not sure what you mean by a "self class"?

> I was wondering if some one could help me create these functionalities in a
> manner similar to the following code. (similar to the Quitcommand
> function).

See my reply to your other post.

> Another question I had, was how to make the status bar text as a variable
> such that it keeps on displaying what is going on in the program?

Its always best to keep separate questions in separate
posts - it makes searching the archives easier in the
future. However,...

That depends on what you want to show in the Status bar. A Status
bar normally includes showing help text when the mouse moves over
widgets and the status of any component that the cursor enters.
That sounds different to what you want?

You may be able to use a StriVar variable linked to an Entry on
the status bar, or maybe even a Label(can a Label text link to
a StrVar? I'm not sure). Alternatively ifv your code controls
where the variable gets changed(as it should) then simply update
the status bar every time you change that variable. This is one
case where a setX type function becomes worthwhile. Then only
change X by calling setX()...

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos


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Re: [Tutor] Copy/Paste in Tkinter

[Alan Gauld via Tutor]

On 04/02/17 00:24, Pooja Bhalode wrote:

> I am trying to write a simple Tkinter code in Python in order to
> demonstrate select/copy/paste/cut functionalities using keyboard keys and
> menu options.

You are going a fairly long winded way about it.
Rather than generating events use the Text/Entry
widget methods directly.

Check the documentation for the following methods:

Text.get()   # copy
Text.selection_get(...) # copy a selection
Text.delete(...)  # cut
Text.insert(...)  # paste

To control selections look at the tag methods,
but that is more complex.

> def show_menu(e):
> w = e.widget
> # the_menu.entryconfigure("Select",command=lambda:
> w.event_generate("<>"))
> the_menu.entryconfigure("Cut",command=lambda: w.event_generate("<>"))
> the_menu.entryconfigure("Copy",command=lambda: w.event_generate("<>"))
> the_menu.entryconfigure("Paste",command=lambda:

These should be in the create function. You don't need
to configure the command every time you show the menu.

> w.event_generate("<>"))
> the_menu.tk.call("tk_popup", the_menu, e.x_root, e.y_root)

You should only need to call the tk.call() method very,
very rarely, there is usually a more direct way to do things.

> root = Tkinter.Tk()
> make_menu(root)
> 
> e1 = Tkinter.Entry(); e1.pack()
> e2 = Tkinter.Entry(); e2.pack()

Shouldn't these Entries have a parent?

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos


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[Tutor] Tkinter Copy/Paste/Cut functionalities

[Pooja Bhalode]

Hi,

I am new to tkinter and looking for some help with select/copy/paste
functionalities. I wish to keep these tabs in the Edit menu and as well as
be able to do it using the shortcut keys.
Here, I am trying to create a GUI and needed some help with that.
I came across some snippets of the code to do this but using a self class.
I was wondering if some one could help me create these functionalities in a
manner similar to the following code. (similar to the Quitcommand
function).

Another question I had, was how to make the status bar text as a variable
such that it keeps on displaying what is going on in the program?

I would really appreciate your help on this.
Thank you so much.

Pooja

Code:

from Tkinter import *
import datetime
import tkMessageBox

root = Tk()
root.title("Name of the interface")

def Doit():
   print "Inside the function"

from tkMessageBox import *

def Quitcommand():
if askyesno('Verify', 'Are you sure you want to quit?'):
if askyesno('Save file', 'Do you want to save the current file?'):
print 'Saving file'
root.quit()
else:
showinfo('Quit not implemented.')

def LoadNew():
print 'Loading new .gPROMS files'
# User enters the name of the to be executed.
if tkMessageBox.askyesno('Reading new file','Do you want to read
in the new files'):
print 'Reading new files. '

def show_about():
print 'HELP function'

from tkFileDialog import askopenfilename

def OpenFile():
name = askopenfilename()
print name

### --- Menu bar  
menu = Menu(root)
root.config(menu=menu)

editmenu = Menu(menu, tearoff=0)
menu.add_cascade(label="Edit", menu=editmenu)

editmenu.add_command(label="Cut",accelerator="Ctrl+X",command=DoCut)
editmenu.add_command(label="Copy",accelerator="Ctrl+C",command=DoCopy)
editmenu.add_command(label="Paste", accelerator="Ctrl+V"command=DoPaste)
editmenu.add_command(label="Make Changes", command=TimeAllowed)
editmenu.add_command(label="Line", command=Doit)


### --- Status bar  
Status = Label(root, text = 'Static',bd=1, relief=SUNKEN, anchor=W)
Status.pack(side=BOTTOM, fill=X)



root.mainloop()
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[Tutor] Copy/Paste in Tkinter

[Pooja Bhalode]

Hi,
I am trying to write a simple Tkinter code in Python in order to
demonstrate select/copy/paste/cut functionalities using keyboard keys and
menu options.
I tried looking up online, but I am finding examples of these in which they
create an event and then it is used:
eg.:

import Tkinter

def make_menu(w):
global the_menu
the_menu = Tkinter.Menu(w, tearoff=0)
# the_menu.add_command(label="Select")
the_menu.add_command(label="Cut")
the_menu.add_command(label="Copy")
the_menu.add_command(label="Paste")

def show_menu(e):
w = e.widget
# the_menu.entryconfigure("Select",command=lambda:
w.event_generate("<>"))
the_menu.entryconfigure("Cut",command=lambda: w.event_generate("<>"))
the_menu.entryconfigure("Copy",command=lambda: w.event_generate("<>"))
the_menu.entryconfigure("Paste",command=lambda:
w.event_generate("<>"))
the_menu.tk.call("tk_popup", the_menu, e.x_root, e.y_root)

root = Tkinter.Tk()
make_menu(root)

e1 = Tkinter.Entry(); e1.pack()
e2 = Tkinter.Entry(); e2.pack()
e1.bind_class("Entry", "", show_menu)

root.mainloop()

I was wondering if someone could please tell me a simplified different way
of doing this, that would be great. Thank you.

Pooja
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