CALL it only IF it is FOR no reason

[npocmaka_]

Here many many ...many moons ago I've wondered why I can't CALL FOR and IF command. But it turned out that this was yet another case when I've underestimated the cmd.exe . It is possible to call IF and FOR:

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@echo off

rem :: this will produce an error
rem if a equ a

rem :: And this too
rem call if a equ a rem

rem :: But this will not!!!
call if a equ a

rem :: This will not too ((\but in command prompt single % is enough)
call for %%%%a in (.) do

rem :: And this
call if a equ a for %%%%a in (.) do if 1 equ 1  for %%%%a in (.) do if c==c

rem :: And this
call if a equ a for %%%%a in (.) do if 1 equ 1 for %%%%a in (.) do if c==c ( rem rem rem echo something

Though it's not useful at all as it does not work if there is finished statement/command after if/for block. But it is an insane bug and shows that the FOR and IF parsers should have something in common.

[Liviu]

Nice topic title

It is possible to call IF and FOR:

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call if a equ a

Don't think that "a equ a" is actually relevant, "call if ???" also "works" i.e. does nothing. More examples in the thread at http://www.dostips.com/forum/viewtopic.php?p=32829#p32829 with some curious findings, but no real resolution.

Liviu

[npocmaka_]

Don't think that "a equ a" is actually relevant, "call if ???" also "works" i.e. does nothing. More examples in the thread at http://www.dostips.com/forum/viewtopic.php?p=32829#p32829 with some curious findings, but no real resolution.

Liviu

Almost every time I think I find something new it's not new . Should search more careful next time.
At least the open bracket behavior and composition of for/if seem to be something new (but at the same degree useless)

My picture of the cmd source code is more like a bowl of spaghetti

Do you have decompiled cmd? My attempts with opensource decompilers failed...

[Squashman]

Do you have decompiled cmd? My attempts with opensource decompilers failed...

I believe someone who posts on this forum did it last year. Trying to find the thread.

[jeb]

Don't think that "a equ a" is actually relevant, "call if ???" also "works" i.e. does nothing.

I assume, that CALL suppress some sorts of parser errors.
So the samples don't work, they only don't show an error message.

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@echo off
set "var1=echo Test1 X & echo Y"
set "var2=echo Test2 X ^& echo Y"

call %%var1%%
call %%var2%%

Test2 X & echo Y

jeb

[Liviu]

My picture of the cmd source code is more like a bowl of spaghetti

Do you have decompiled cmd? My attempts with opensource decompilers failed...

No, that would kill all fun of trying to second guess it Besides, my take on decompilers is along the line of (paraphrased) "can't bring a cow back from hamburgers".

I assume, that CALL suppress some sorts of parser errors.
So the samples don't work, they only don't show an error message.

Right. Now that you mentioned it, there even appears to be an errorlevel returned.

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C:\tmp>(call if ???) && (echo OK) || (echo failed)
failed

Liviu

[npocmaka_]

One more thing that started to bother me with CALL.If you call something in in brackets it wont be executed:

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call (echo "I just call to say I love you")

Even non-existent commands wont produce an error:

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call ( gibberish) && echo successful execution

the only things that annoys CALL are some parsing errors:

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call  ( if a=
 call ( :%~ gives an error only from a batch file )
call (^)

[npocmaka_]

Call parser is pretty buggy . Here are more strange cases for CALL with brackets:

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>call ((echo TEST)

>call (( echo TEST ))
'1' is not recognized as an internal or external command,
operable program or batch file.

>call ( @echo TEST )
'9' is not recognized as an internal or external command,
operable program or batch file.

>echo @echo echo from 1.bat >1.bat

>echo @echo echo from 9.bat >9.bat

>call (( echo TEST ))
echo from 1.bat

>echo (@echo TEST)
(@echo TEST)

>call (echo /?)
....call help...

When CALL is used with an expression with more than one pair of brackets it searches (at least on my machine) for "1" program/script
(and if exists it will be executed)

If something that looks like (@ whatever ) it will search for "9" program command and if exist will be executed.


If there somewhere /? string (but not in quotes) in the argument passed to the CALL it will print the CALL help without appeal . E.G CALL CMD /? will print CALL help .
Also it's with higher priority than calling a label (same with GOTO)