comp.lang.idl-pvwave archive: archive » Re: IDL interpreter questions - can someone (D.Fanning) explain

Home » Public Forums » archive » Re: IDL interpreter questions - can someone (D.Fanning) explain - TIA

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: IDL interpreter questions - can someone (D.Fanning) explain - TIA [message #25084 is a reply to message #25075]

Fri, 18 May 2001 12:31

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

<mankoff@I.HATE.SPAM.lasp.colorado.edu> writes:

> On Fri, 18 May 2001, JD Smith wrote:
>
>> dadada wrote:
>>> How are variables referenced by default?
>> I'm not sure what you mean here. Pointer references? They are explicit
>> only... i.e. you can't create a reference of an existing variable.
>
> Not sure either, but here is my interpretation of the question/answer:
>
> In functions, variables are *always* 'by value'
> In procedures, they are 'by value' unless you put a "return" statement
> anywhere in the procedure. If this exists, then they are passed 'by
> reference'

Sorry Ken I'm going to have to take you to task for a few things.
First of all, pass by value vs. pass by reference:

* all variables are passed by reference, *except*
* subscripted arrays, structure tags, and (I believe) system variables,
which are passed by value

It doesn't make a difference whether you have a return statement or
not.

As for continuations, closures, etc., these are computer science
jargon for specific language behaviors. IDL has none of them. I
understand continuations to be a way for execution contexts to be
suspended, saved, and later restored. Perhaps the CATCH error
handling technique is a nascent continuation. Alas, this has nothing
to do with the CONTINUE reserved word recently added to FOR and WHILE
loops.

Craig

--
------------------------------------------------------------ --------------
Craig B. Markwardt, Ph.D. EMAIL: craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
------------------------------------------------------------ --------------

Report message to a moderator

[Message index]

		Re: IDL interpreter questions - can someone (D.Fanning) explain - TIA By: <mankoff[1] on Fri, 18 May 2001 17:17
		Re: IDL interpreter questions - can someone (D.Fanning) explain - TIA By: Craig Markwardt on Fri, 18 May 2001 12:31
		Re: IDL interpreter questions - can someone (D.Fanning) explain - TIA By: John-David T. Smith on Tue, 22 May 2001 13:41
		Re: IDL interpreter questions - can someone (D.Fanning) explain - TIA By: Craig Markwardt on Sat, 19 May 2001 10:20
		Re: IDL interpreter questions - can someone (D.Fanning) explain - TIA By: Mark Rivers on Fri, 18 May 2001 22:28

Previous Topic:	Re: Checkbox Starting Checked
Next Topic:	Re: [Newbie]writing JPEG or GIF file with plot?

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Sat Oct 11 05:27:43 PDT 2025

Total time taken to generate the page: 0.96184 seconds