Re: [racket-users] Re: How to differentiate between files and directories?

[WarGrey Gyoudmon Ju]

Maybe you can work with (namespace-mapped-symbols) and
(namespace-variable-value),
All field accessors are procedures with name starts with "struct-name-", no
duplicates in the entire application.

On Fri, Jul 22, 2016 at 3:59 AM, David Storrs 
wrote:

> So there's no way to query the interface of a struct?
>
>
> On Thursday, July 21, 2016, Jon Zeppieri  wrote:
>
>>
>>
>> On Thu, Jul 21, 2016 at 2:44 PM, David Storrs 
>> wrote:
>>>
>>>
>>>
>>> In a related question, is there a way to introspect a struct to find
>>> out what its fields are?
>>>
>>>
>> If you mean the field values: yes, but only if the struct is transparent
>> or prefab or if you have the proper inspector, which you probably do not.
>> You can generally try struct->vector and see if you get anything useful.
>>
>> If you mean the field names: I don't think so; I don't think they exist
>> at runtime.
>>
>> - Jon
>>
>>
>>
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[racket-users] Re: How to differentiate between files and directories?

[David Storrs]

Okay. Thanks for the help, all.

On Thursday, July 21, 2016, Jon Zeppieri  wrote:

>
>
> On Thu, Jul 21, 2016 at 3:59 PM, David Storrs  > wrote:
>
>> So there's no way to query the interface of a struct?
>>
>>
>>
> Not in general, no. -J
>
>
>

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[racket-users] Re: How to differentiate between files and directories?

[Jon Zeppieri]

On Thu, Jul 21, 2016 at 3:59 PM, David Storrs 
wrote:

> So there's no way to query the interface of a struct?
>
>
>
Not in general, no. -J

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[racket-users] Re: How to differentiate between files and directories?

[David Storrs]

So there's no way to query the interface of a struct?

On Thursday, July 21, 2016, Jon Zeppieri  wrote:

>
>
> On Thu, Jul 21, 2016 at 2:44 PM, David Storrs  > wrote:
>>
>>
>>
>> In a related question, is there a way to introspect a struct to find
>> out what its fields are?
>>
>>
> If you mean the field values: yes, but only if the struct is transparent
> or prefab or if you have the proper inspector, which you probably do not.
> You can generally try struct->vector and see if you get anything useful.
>
> If you mean the field names: I don't think so; I don't think they exist at
> runtime.
>
> - Jon
>
>
>

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Re: [racket-users] How to differentiate between files and directories?

[Jon Zeppieri]

On Thu, Jul 21, 2016 at 2:44 PM, David Storrs 
wrote:
>
>
>
> In a related question, is there a way to introspect a struct to find
> out what its fields are?
>
>
If you mean the field values: yes, but only if the struct is transparent or
prefab or if you have the proper inspector, which you probably do not. You
can generally try struct->vector and see if you get anything useful.

If you mean the field names: I don't think so; I don't think they exist at
runtime.

- Jon

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[racket-users] Re: How to differentiate between files and directories?

[David Storrs]

Hi Stephen,

Yep, I saw file-exists?, thanks. Like I said, I don't want to check the
disk twice (once when getting the list of paths with (in-directory), then
again with file-exists?). I don't care if the file actually exists on disk,
I care if this path is describing a file or a directory. I'm hoping to be
able to do something like, e.g., use (fold-files) or (find-files)
to process just files or just directories.

On Thursday, July 21, 2016, Stephen De Gabrielle 
wrote:

>
> http://docs.racket-lang.org/reference/Filesystem.html#%28def._%28%28quote._~23~25kernel%29._file-exists~3f%29%29
>
> in http://docs.racket-lang.org/reference/Filesystem.html
>
>
>
> (file-exists?
> 
>  path) → boolean?
> 
> (link-exists?
> 
>  path) → boolean?
> 
>
> (directory-exists?
> 
>  path) → boolean?
> 
>
>   path : path-string?
> 
>
> Returns #t if path refers to a directory, #f otherwise.
>
>
> On Thu, Jul 21, 2016 at 7:44 PM, David Storrs  > wrote:
>
>> Silly question: given a <#path>, how do I tell if it's to a file,
>> directory, link, etc?  I'd like to know this in general, although the
>> proximate issue is that I would like to use (in-directory) to process
>> all the files in a directory, but I need a way to ignore everything
>> that isn't a file.
>>
>> I saw 'file-exists?' but I don't want to check the disk twice, I just
>> want to know what type it is.  That information should have been
>> available when the path was constructed.
>>
>>
>> In a related question, is there a way to introspect a struct to find
>> out what its fields are?
>>
>>
>> Dave
>>
>> --
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>> "Racket Users" group.
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>> 
>> .
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>>
>
>

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Re: [racket-users] How to differentiate between files and directories?

[Jon Zeppieri]

On Thu, Jul 21, 2016 at 2:44 PM, David Storrs 
wrote:

>
>
> I saw 'file-exists?' but I don't want to check the disk twice, I just
> want to know what type it is.  That information should have been
> available when the path was constructed.
>
>
Constructing a path doesn't require checking the filesystem, because a path
might not actually refer to anything extant. E.g.,

> (string->path "/foo/bar")
#

(There is nothing on my filesystem at /foo/bar.)

- Jon

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Re: [racket-users] How to differentiate between files and directories?

[Stephen De Gabrielle]

http://docs.racket-lang.org/reference/Filesystem.html#%28def._%28%28quote._~23~25kernel%29._file-exists~3f%29%29

in http://docs.racket-lang.org/reference/Filesystem.html



(file-exists?

 path) → boolean?

(link-exists?

 path) → boolean?


(directory-exists?

 path) → boolean?


  path : path-string?


Returns #t if path refers to a directory, #f otherwise.


On Thu, Jul 21, 2016 at 7:44 PM, David Storrs 
wrote:

> Silly question: given a <#path>, how do I tell if it's to a file,
> directory, link, etc?  I'd like to know this in general, although the
> proximate issue is that I would like to use (in-directory) to process
> all the files in a directory, but I need a way to ignore everything
> that isn't a file.
>
> I saw 'file-exists?' but I don't want to check the disk twice, I just
> want to know what type it is.  That information should have been
> available when the path was constructed.
>
>
> In a related question, is there a way to introspect a struct to find
> out what its fields are?
>
>
> Dave
>
> --
> You received this message because you are subscribed to the Google Groups
> "Racket Users" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to racket-users+unsubscr...@googlegroups.com.
> For more options, visit https://groups.google.com/d/optout.
>

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[racket-users] How to differentiate between files and directories?

[David Storrs]

Silly question: given a <#path>, how do I tell if it's to a file,
directory, link, etc?  I'd like to know this in general, although the
proximate issue is that I would like to use (in-directory) to process
all the files in a directory, but I need a way to ignore everything
that isn't a file.

I saw 'file-exists?' but I don't want to check the disk twice, I just
want to know what type it is.  That information should have been
available when the path was constructed.


In a related question, is there a way to introspect a struct to find
out what its fields are?


Dave

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