Re^3: sub calls and memory use

See goto. You pass arguments in @_, as always.

Of course, when calling any function, the call stack still grows since the return address needs to be stored on the call stack. This is independent of any function parameters (or none) passed to the next recursive invocation.

Update: As the replies below also point out, I answered too quickly. I thought you were still calling the function but with empty parameters. If you're using goto to transfer control to the function, there should be no memory growth, as the replies also say.

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Re^4: sub calls and memory use by LanX (Saint) on Nov 16, 2019 at 14:55 UTC
> the call stack still grows since the return address needs to be stored on the call stack. I'm pretty sure that this is not needed because you can't return to the source of a goto. If it's stored nevertheless than it's for vain. But I really doubt this because the docs clearly say that even caller can't tell where the call happened. IMHO goto &sub was never optimized to allow tail call optimizations, it's main purpose is the use in AUTOLOAD. Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery FootballPerl is like chess, only without the dice}	[reply]
Re^5: sub calls and memory use by dave_the_m (Monsignor) on Nov 16, 2019 at 15:30 UTC
I'm pretty sure that this is not needed because you can't return to the source of a goto Indeed, goto &foo pops the current call frame and replaces it with a new frame, rather than just pushing an additional one as a normal sub call would do. The following consumes lots of CPU but uses constant memory: `sub foo { goto &foo }; foo();` [download] Dave.	[reply] [d/l]
Re^4: sub calls and memory use by Anonymous Monk on Nov 16, 2019 at 14:43 UTC
You pass arguments in @_, as always. So I was just using the wrong global variable! I can see now that pushing my arg into @_ before the &sub call prevents memory growth. Thank you Corion.	[reply]
Re^5: sub calls and memory use by LanX (Saint) on Nov 16, 2019 at 15:03 UTC
In Perl you are generally better off translating tail calls to loops. They are way faster and easier to understand. You never explained your use case, but your example is easily translated with `redo` Concerning your memory growth, we'd need to know how you declared the "global var". Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery FootballPerl is like chess, only without the dice}	[reply]
Re^6: sub calls and memory use by Anonymous Monk on Nov 16, 2019 at 15:35 UTC
In Perl you are generally better off translating tail calls to loops. I replaced that recursive sub with a while loop and yeah, makes more sense, less code, and no memory bomb. ThanX Concerning your memory growth, we'd need to know how you declared the "global var". Sorry I was mistaken about that :-/	[reply]