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Re: set variables, in mass
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Re: set variables, in mass


  • Subject: Re: set variables, in mass
  • From: kai <email@hidden>
  • Date: Wed, 1 Dec 2004 04:14:58 +0000


On Wed, 1 Dec 2004 12:26:03 +1100, "halloolli" wrote:

set a to 0 -- a now has 0
copy a to b -- b now has 0

is there any difference between set and copy?

In some circumstances - particularly those relating to lists, records and script objects, where data sharing may be involved.


Compare these results:

============

set x to {1}
set y to x
set x's item 1 to 10
x - y
--> 0

------------

set x to {1}
copy x to y
set x's item 1 to 10
x - y
--> 9

============

- or these:

============

set x to current date
set y to x
set x's year to 2005
x - y
--> 0

------------

set x to current date
copy x to y
set x's year to 2005
x - y
--> 31536000

============

Details of the differences between set and copy, along with an explanation of data sharing, can be found in the AppleScript Language Guide (ASLG):

Set:
http://developer.apple.com/documentation/AppleScript/Conceptual/ AppleScriptLangGuide/AppleScript.75.html#10267


Copy:
http://developer.apple.com/documentation/AppleScript/Conceptual/ AppleScriptLangGuide/AppleScript.66.html#21248


Data Sharing:
http://developer.apple.com/documentation/AppleScript/Conceptual/ AppleScriptLangGuide/AppleScript.9a.html#23480


In spite of a lack of recent updates, the ASLG is still - IMO - a document well worth reading and keeping to hand:

HTML:
http://developer.apple.com/documentation/AppleScript/Conceptual/ AppleScriptLangGuide/index.html


Download PDF:
http://developer.apple.com/documentation/AppleScript/Conceptual/ AppleScriptLangGuide/AppleScriptLanguageGuide.pdf


(The latter may appear to merely open a blank browser window - in which case check your Downloads window.)

---
kai

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