Re: file objects
Re: file objects
- Subject: Re: file objects
- From: Axel Luttgens <email@hidden>
- Date: Sun, 28 Feb 2010 22:52:12 +0100
Le 27 févr. 2010 à 18:41:58, Thomas Fischer a écrit :
> Hello,
>
> I ran into some problems with file objects and am wondering if I misunderstood something and/or how to treat them correctly (in the background is the problem of the three different ways AppleScript refers to elements of the file system).
>
> I can say
> set myFile to alias "Macintosh HD:Examples:03.pdf"
> but I get an error for
> set myFile to file "Macintosh HD:Examples:03.pdf"
>
> To get a file object, I seem to need an application.
>
> I can try the Finder:
>
> tell application "Finder" to set myFile to file "Macintosh HD:Examples:03.pdf"
> --> document file "03.pdf" of folder "Examples" of startup disk
> set myClass to class of myFile
> --> document file
>
> so this is a "document file", not a file.
>
> Or I can try System Events:
>
> tell application "System Events" to set myFile to file "Macintosh HD:Examples:03.pdf"
> --> file "Macintosh HD:Examples:03.pdf"
> set myClass to class of myFile
> --> file
>
> Or without an application I can use a POSIX path, trusting that "the result of evaluating a POSIX file specifier is a file object":
>
> set myFile to POSIX file "/Examples/03.pdf"
> -->file "Macintosh HD:Examples:03.pdf"
> set myClass to class of myFile
> -->«class furl»
>
> So this is not a file object.
>
> The AppleScript Language Guides claims "AppleScript supports coercion of a file object to a text", but funnily enough, from the above results the file object obtained from System Events is the only one that cannot be coerced to text but gives an error message.
>
> Can anybody illuminate the situation?
Hello Thomas,
The ASLG always has required some caution while reading those matters about files; moreover, things have evolved more or less silently.
In the ASLG for 1.3.7, one may read:
You can obtain a file specification from the New File scripting
addition command distributed with AppleScript, or from an
application command that returns a file specification.
[...]
set fileSpec to new file default name "New Report"
class of fileSpec --result: file specification
In the ASLG for 2.0:
You can use a file object to specify a name and location for a
file that may not exist:
set newFile to POSIX file "/Users/myUser/BrandNewFile.rtf"
Similarly, you can let a user specify a new file with the choose
file name (page 118) command, then use the returned file object
to create the file.
Strictly speaking, your negative result with
set myFile to file "Macintosh HD:Examples:03.pdf"
thus doesn't contradict the ASLG.
Now, let's try this one:
choose file name
--> file "Some volume:some:path:to:some:file"
class of result
--> «class furl»
So, both "POSIX file" and "choose file name" return objects displayed the same way in the log and belonging to the same class.
Assuming file "Macintosh HD:Examples:03.pdf" exists, you may thus try:
alias "Macintosh HD:Examples:03.pdf" as «class furl»
--> file "Macintosh HD:Examples:03.pdf"
class of result
--> «class furl»
HTH,
Axel
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| | >file objects (From: Thomas Fischer <email@hidden>) |