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Author Topic: 'DROP' mnemonic with ERR= clause  (Read 1751 times)

James Zukowski

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'DROP' mnemonic with ERR= clause
« on: September 05, 2023, 12:04:38 PM »
Is including an ERR= clause in the 'DROP' mnemonic a valid construct? e.g.:
print 'drop'(Win_Num,err=*next),
It doesn't generate an error, but it also doesn't seem to trap error #57 if the specified (non-zero) window# doesn't exist.
Any insights?
James Zukowski
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Re: 'DROP' mnemonic with ERR= clause
« Reply #1 on: September 05, 2023, 02:32:56 PM »
The ERR= should be on the print, not on the mnemonic.

e.g.  PRINT (0,ERR-*next) 'DROP'(Win_num),

James Zukowski

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Re: 'DROP' mnemonic with ERR= clause
« Reply #2 on: September 05, 2023, 03:16:45 PM »
Thanks. Just surprised it's not a syntax error.
James Zukowski
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Re: 'DROP' mnemonic with ERR= clause
« Reply #3 on: September 05, 2023, 03:22:31 PM »
Technically the 'DROP' mnemonic is really just a function that returns the escape sequence required to drop the specified window.

For example its perfectly legal to code:

   X$ = 'DROP'(win_num)

This will result in an escape sequence that can be output to console (channel 0).  Any/all mnemonics are really just escape sequences that can be output to a device.

As for the ERR= clause, it would have been triggered if the window number was invalid (such as a negative number or non-integer)