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Forum Index : Microcontroller and PC projects : CMM2: RUNning a program named by a variable$ or string-expression

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thwill

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Joined: 16/09/2019
Location: United Kingdom
Posts: 4302

Posted: 12:54pm 28 Jun 2020

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The following post contains attributions to both matherp and TassyJim. I apologise in advance for any innaccuracies or misrepresentation.

I've come across this limitation in my development work and thought I would share in the event that others hit the same.

MMBasic on the CMM2 requires the target of a RUN statement to be a string literal , i.e. it doesn't allow you to do the following:

s$ = "foobar.bas"
Run s$

TassyJim suggested a workaround equivalent to the following:

s$ = "foobar.bas"
Open "/tmp.bas" For Output As s#1
Print #1, "Run " + Chr$(34) + s$ + Chr$(34)
Run "/tmp.bas"

But matherp said "This is a ... bad idea and causes the flash to be re-written twice." I think this argument was regarding wearing out the flash on the microcontroller, but it may also have been a comment on performance.

I thought some more about it and believe the following should work without the double-hit on the flash:

s$ = "foobar.inc"
Open "/tmp.bas" For Output As s#1
Print #1, "#Include " + Chr$(34) + s$ + Chr$(34)
Run "/tmp.bas"

Though it does require you to provide foobar as a .inc file instead of a .bas file. Of course if you also need to execute foobar standalone you can just have a parallel foobar.bas file consisting of a single #Include statement.

Best regards,

Tom
Edited 2020-06-28 22:59 by thwill

MMBasic for Linux, Game*Mite, CMM2 Welcome Tape, Creaky old text adventures

thwill

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Joined: 16/09/2019
Location: United Kingdom
Posts: 4302

Posted: 08:02pm 28 Jun 2020

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Dang! it doesn't work in the general case because .inc files are not allowed to #Include other .inc files

I guess I have to try an persuade Peter to make more changes

EDIT: and it would also be limited by the fact that #Include does not support absolute paths.

Tom
Edited 2020-06-29 07:24 by thwill

MMBasic for Linux, Game*Mite, CMM2 Welcome Tape, Creaky old text adventures

thwill

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Joined: 16/09/2019
Location: United Kingdom
Posts: 4302

Posted: 12:48pm 01 Jul 2020

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I have been thinking some more about this and there are two related use-cases I'm seeking a solution for:

1. RUN a program where its name comes from a string expression.

2. RUN a program using the * command where that program is not situated in SEARCH PATH
�- some programs have additional .inc files and use other file resources you don't want to copy into SEARCH PATH and you don't want to use absolute paths to.
�- you don't want to hit the flash twice so the "solution" of having a stub file in SEARCH PATH that calls RUN on the real file is undesireable.

I believe there is a single solution to both, and looking at the MMBasic source (Pi version) it doesn't look too difficult to implement:

a. You define a .lnk file type that contains a single line containing the path of a .bas file to run.
- ideally it would also allow comments because I'm interested in autogenerating these files and autogenerated files should always indicate their origin.

b. When we use RUN or * and the file argument specifies a .lnk file then MMBasic reads that file and RUNs (i.e. "FileLoadProgram") the program specified therein.

This fixes problem (1) as follows:

s$ = "A:/subdir/foobar.bas"
Open "/tmp.lnk" For Output As s#1
Print #1, s$
Run "/tmp.lnk"

And for problem (2):

If you create a file "zmim.lnk" in the SEARCH PATH containing:

/zmim/src/main.bas

Then typing *zmim would RUN /zmim/src/main.bas with only a single hit on the flash.

Thanks for reading,

Tom
Edited 2020-07-01 23:14 by thwill

MMBasic for Linux, Game*Mite, CMM2 Welcome Tape, Creaky old text adventures

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