Maybe I've not been clear, but what I'm most interested in, is to know whether an object would be passed by value, being a copy of the original, when specified. I thought it was NEVER, but Chris - with all respect - says this is a rumour?

See where the rumour comes from (for example):

http://codeverge.com/sybase.powerbuilder.general/pass-by-reference-vs-java-pass-by/1017088

or even from the pb help:

From the help of pb 2019, I find the information confusing and guess I'll just have to do a test app passing huge objects and see if memory is affected when passing an object by value, vs. passing readlonly and by ref.

Thanks you all for answering.

Miguel,

Objects are never copied when passing them as arguments either by value, by reference, or by read only. What gets copied or referenced is the reference (pointer) to the object, not the object itself. So any changes to the object inside the function will change the object that was created outside of it.

Passing by value makes a copy of the pointer. If you change it, the original pointer remains unaffected. Passing by reference passes the pointer by reference and if you change it the original pointer will get changed. Passing by read only is similiar to by reference but you cannot change the pointer. I don't see any possible speed improvement of using either of the three.

Simple variables and structures behave differently. Just as you would expect when using either by value, by reference, or by read only as their name implies. Passing by value makes a copy of the variable or structure so if the content of the variable or structure is large there is some speed improvement by using by reference or by read only, although maybe not detectable due to the speed of today's machines.

Regards, Ricardo

Hi Miguel;

  That rumor is false. They are passed as defined.

For performance through-put in an intense processing loop for example, you should always try to pass method arguments by either Read-Only or Reference.   ;-)

Regards ....Chris

Hi, Miguel -

Lacking familiarity with your application, about all I can say is: "it depends".

Modern CPU's & graphics cards are so blazing fast anymore that unless your app makes a LOT of function calls in a short period of time and/or passes large amounts of information from the calling code to the called code on a routine basis, I would hesitate to pass all or most function arguments by reference only in the hope of gaining a teeny-tiny boost in performance, but my opinion is based on the history of the types of apps I've worked on over the years...none of these needed to resort to this coding technique. That said - I think you're the only/best one qualified to make this call.

If you go this route, I'd include a notification/disclaimer in each applicable function script that states you're passing arguments by ref on purpose to boost performance by reducing the amount of data passed into the function. Code can outlive us, and self-documenting code is never a bad thing in my book.

Regards, John