Call bug using silent operator @

[carlos]

Developing a project related to batch I found that the CALL internal command has a bug.
It not execute the command if you use the silent operator @.

For example:

Code: Select all

@call vol

Is different than:

Code: Select all

call @vol

The later not execute the command.

This can be used as another way of write a single line comment

Code: Select all

call @ Single line comment

[IcarusLives]

While this is a very interesting find, it is SUBSTANTIALLY slower than using REM

Code: Select all

@echo off

echo %time%
for /l %%a in (1,1,1000000) do rem
echo %time%
echo.
echo %time%
for /l %%a in (1,1,1000000) do call @ this is a comment
echo %time%

pause

Code: Select all

14:49:04.92
14:49:06.18

14:49:06.18
14:50:37.22
Press any key to continue . . .

[dbenham]

Developing a project related to batch I found that the CALL internal command has a bug.
It not execute the command if you use the silent operator @.

Yes - that is known behavior. We documented that in Phase 6 of the batch parsing rules at StackOverflow. There are a number of constructs that function as a REM if combined with CALL.

Phase 6) CALL processing/Caret doubling: . . .

• . . .
• Remove the first CALL so multiple CALL's can be stacked
• . . .
• Restart phases 1, 1.5, and 2, but do not continue to phase 3
  • . . .
  • Phase 2 tasks are altered a bit
    • . . .
    • The CALL is aborted without error if any of the following are detected
      • Newly appearing unquoted, unescaped & or |
      • The resultant command token begins with unquoted, unescaped (
      • The very first token after the removed CALL begins with @
• . . .

There are other Phase 6 peculiarities that I omitted above. Read the StackOverflow post for more info.


Dave Benham