Re: Getting nice print of struct for debugging
On Saturday, 25 February 2017 at 01:30:09 UTC, Minty Fresh wrote:
On Saturday, 25 February 2017 at 01:27:09 UTC, Minty Fresh
wrote:
On Wednesday, 22 February 2017 at 11:18:15 UTC, Martin
Tschierschke wrote:
[...]
Since structs are Plain-old Data and don't do inheritance, the
best option is a template mixin.
ie.
template mixin PrettyPrint
{
string toString()
{
// . . .
}
}
From there, you can mix it into any struct you want.
struct MyStruct
{
mixin PrettyPrint;
}
If you're familiar with Rails, this is similar to a Concern.
Errata on that. Should actually be declared as:
mixin template PrettyPrint()
This is why I shouldn't make posts from my phone.
Thank you, but this solution from Kevin Brogan, is an good
alternative,
to add a special dump function globally, so no need to modify the
struct definitions.
https://forum.dlang.org/post/yewavntuyutdvejwj...@forum.dlang.org
His solution:
import std.traits;
void main()
{
WSADATA wsa;
dump!wsa;
}
void dump(alias variable)()
{
writeln("\nDumping ",typeid(typeof(variable)),":\n");
writeln(variable.stringof, " = \n{");
foreach(member; FieldNameTuple!(typeof(variable)))
{
writeln("\t", member, ": ", mixin("variable."~member) );
}
writeln("}\n");
}
Re: Getting nice print of struct for debugging
On Saturday, 25 February 2017 at 01:27:09 UTC, Minty Fresh wrote:
On Wednesday, 22 February 2017 at 11:18:15 UTC, Martin
Tschierschke wrote:
[...]
Since structs are Plain-old Data and don't do inheritance, the
best option is a template mixin.
ie.
template mixin PrettyPrint
{
string toString()
{
// . . .
}
}
From there, you can mix it into any struct you want.
struct MyStruct
{
mixin PrettyPrint;
}
If you're familiar with Rails, this is similar to a Concern.
Errata on that. Should actually be declared as:
mixin template PrettyPrint()
This is why I shouldn't make posts from my phone.
Re: Getting nice print of struct for debugging
On Wednesday, 22 February 2017 at 11:18:15 UTC, Martin
Tschierschke wrote:
On Tuesday, 21 February 2017 at 14:02:54 UTC, Jacob Carlborg
wrote:
[...]
Yes, this works, I would say this is the simplest:
MyStruct s;
foreach (index, name ; FieldNameTuple!MyStruct)
writefln("%s: %s", name, s.tupleof[index]);
If you want something more close to "send" in Ruby, you need
to use a string mixin, like this:
foreach (name ; FieldNameTuple!MyStruct)
writefln("%s: %s", name, mixin("s." ~ name));
The string mixin example works for methods, opDispatch and
similar as well. The tupleof example, the first one, works
only for fields.
Exactly what I was looking for, **thank you!**
Both ways of accessing the struct elements are very interesting,
giving an impression what is possible with D.
Is it possible to overwrite "toString" for all structs in one
step?
Regards mt.
Since structs are Plain-old Data and don't do inheritance, the
best option is a template mixin.
ie.
template mixin PrettyPrint
{
string toString()
{
// . . .
}
}
From there, you can mix it into any struct you want.
struct MyStruct
{
mixin PrettyPrint;
}
If you're familiar with Rails, this is similar to a Concern.
Re: Getting nice print of struct for debugging
On 2017-02-22 12:18, Martin Tschierschke wrote: Exactly what I was looking for, **thank you!** Both ways of accessing the struct elements are very interesting, giving an impression what is possible with D. Is it possible to overwrite "toString" for all structs in one step? It depends. You can create a template mixin containing the implementation of toString, which need to be mixed in in all structs. Or you can create a new function that can convert any passed in structs in a generic way. It depends on what you need the string for. -- /Jacob Carlborg
Re: Getting nice print of struct for debugging
On Tuesday, 21 February 2017 at 14:02:54 UTC, Jacob Carlborg
wrote:
[...]
Yes, this works, I would say this is the simplest:
MyStruct s;
foreach (index, name ; FieldNameTuple!MyStruct)
writefln("%s: %s", name, s.tupleof[index]);
If you want something more close to "send" in Ruby, you need to
use a string mixin, like this:
foreach (name ; FieldNameTuple!MyStruct)
writefln("%s: %s", name, mixin("s." ~ name));
The string mixin example works for methods, opDispatch and
similar as well. The tupleof example, the first one, works only
for fields.
Exactly what I was looking for, **thank you!**
Both ways of accessing the struct elements are very interesting,
giving an impression what is possible with D.
Is it possible to overwrite "toString" for all structs in one
step?
Regards mt.
Re: Getting nice print of struct for debugging
On 2017-02-20 17:04, Martin Tschierschke wrote:
Hello,
I have a little program where I am filling a struct with values from an
regex match.
Now I want to display the content of the struct for debugging purpose.
If struct is named MyStruct
I can print a list of the field names with:
foreach(fieldname;FieldNameTuple!MyStruct){writef("%s ",fieldname);}
If myvar is of type MyStruct how can I make a table like:
fieldname_1: value_1
fieldname_2: value_2
.
.
fieldname_n: value_n
Is there a way to do this with a single expression in D.
Similar to a ruby call myvar.send(fieldname) to get the value from
fieldname inside a loop?
write(myvar); sure is working directly but I want to get the field names
displayed, too.
(A work around might be work with the format("%s",myvar) string and
extract the values with an index?)
Yes, this works, I would say this is the simplest:
MyStruct s;
foreach (index, name ; FieldNameTuple!MyStruct)
writefln("%s: %s", name, s.tupleof[index]);
If you want something more close to "send" in Ruby, you need to use a
string mixin, like this:
foreach (name ; FieldNameTuple!MyStruct)
writefln("%s: %s", name, mixin("s." ~ name));
The string mixin example works for methods, opDispatch and similar as
well. The tupleof example, the first one, works only for fields.
--
/Jacob Carlborg
Re: Getting nice print of struct for debugging
On Monday, 20 February 2017 at 16:18:58 UTC, Paul Backus wrote:
On Monday, 20 February 2017 at 16:04:17 UTC, Martin
Tschierschke wrote:
Hello,
I have a little program where I am filling a struct with
values from an regex match.
Now I want to display the content of the struct for debugging
purpose.
I believe the easiest way to do this is to define a custom
toString member function for your struct. For example:
struct MyStruct {
int x;
double y;
string s;
string toString() {
import std.format: format;
return "MyStruct(x: %d, y: %f, s: \"%s\")".format(x, y,
s);
}
}
void main() {
import std.stdio: writeln;
MyStruct foo;
foo.x =2; foo.y = 3.14; foo.s = "the quick brown fox";
writeln(foo); // Prints MyStruct(x: 2, y: 3.14, s: "the
quick brown fox")
}
Good suggestion, thank you! Then the definition is near the
struct definition and I do not need to care about what to call,
just writeln(myvar); cool!
Re: Getting nice print of struct for debugging
On Monday, 20 February 2017 at 16:04:17 UTC, Martin Tschierschke
wrote:
Hello,
I have a little program where I am filling a struct with values
from an regex match.
Now I want to display the content of the struct for debugging
purpose.
I believe the easiest way to do this is to define a custom
toString member function for your struct. For example:
struct MyStruct {
int x;
double y;
string s;
string toString() {
import std.format: format;
return "MyStruct(x: %d, y: %f, s: \"%s\")".format(x, y,
s);
}
}
void main() {
import std.stdio: writeln;
MyStruct foo;
foo.x =2; foo.y = 3.14; foo.s = "the quick brown fox";
writeln(foo); // Prints MyStruct(x: 2, y: 3.14, s: "the
quick brown fox")
}
Getting nice print of struct for debugging
Hello,
I have a little program where I am filling a struct with values
from an regex match.
Now I want to display the content of the struct for debugging
purpose.
If struct is named MyStruct
I can print a list of the field names with:
foreach(fieldname;FieldNameTuple!MyStruct){writef("%s
",fieldname);}
If myvar is of type MyStruct how can I make a table like:
fieldname_1: value_1
fieldname_2: value_2
.
.
fieldname_n: value_n
Is there a way to do this with a single expression in D.
Similar to a ruby call myvar.send(fieldname) to get the value
from fieldname inside a loop?
write(myvar); sure is working directly but I want to get the
field names displayed, too.
(A work around might be work with the format("%s",myvar) string
and extract the values with an index?)
Regards mt.
