LB Booster - handle variable with files

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handle variable with files

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Richard Russell
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Re: handle variable with files
« Reply #2 on: May 19^th, 2017, 3:45pm »

on May 17^th, 2017, 6:58pm, Richard Russell wrote:

If it works successfully in LB4 I think that's an anomaly, since my understanding is that handle variables can't be used in an OPEN statement.

Just to confirm that I've checked the LB4 documentation and nowhere is there any suggestion that a handle variable can be used in an OPEN statement: none of the examples show that and the description of the statement only mentions the use of a regular handle.

If the OP's report is correct and you can, at least in some circumstances, use a handle variable this is another example of LB working differently from what the documentation states. I would not consider the usage to be safe, and it does not work in LBB.

The correct, documented, method is to use MAPHANDLE as I showed in my example, which works in both LB 4 and LBB.

Richard.

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Richard Russell
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Re: handle variable with files
« Reply #3 on: May 25^th, 2017, 4:42pm »

on May 19^th, 2017, 3:45pm, Richard Russell wrote:

If the OP's report is correct and you can, at least in some circumstances, use a handle variable...

The report is not correct. The listed code which purports to demonstrate it working does nothing of the kind, as can be shown by running this example in LB 4.04:

Code:

    fn = fn+1
    hvar$ = "#B" + str$(fn)
    print hvar$
    open "\temp\errors.txt" for input as #hvar$
    print hvar$
    line input #B1, s$ 
    print s$
    close #hvar$

Printing hvar$ after the file has been opened shows that rather than the OPEN statement having opened the file with the handle #B1 as the OP claimed, it has in fact been opened with the handle #hvar1, so a subsequent attempt to read from the file with the expected handle given as a literal fails.

Richard.

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