CODEWITHSUNDEEP
tcltclsh
meolic
meolic

Reputation: 1207

Loading tcl extension from tclsh

I have a C extension to Tcl where command mytest is defined. The extension is compiled correctly (I am on Linux, extension is *.so). For example, I can start tclsh and use it like this:

$ tclsh
% load /path/extension.so
% mytest abc
...

But, if I create a file myscript.tcl with the following content:

load /path/extension.so
mytest abc

then I get error:

$ tclsh myscript.tcl 
invalid command name "mytest"
    while executing
"mytest abc"
    (file "myscript.tcl" line 2)

I am using bash on Ubuntu 14.04. Tcl 8.6.

EDIT 1: My question/problem is that I want to use tclsh with a script as an argument - this script should properly load extensions in such a way that mytest and other implemented functions are working without error.

EDIT 2: Uhh, If I use command "source myscript.tcl" inside tcl shell the result is the same. If I use absolute path for myscript.tcl the error is still the same --- "load" executes without warning but I am not sure about it because I get invalid command name "mytest". Maybe the problem is with scope, but it is working correctly when tclsh is used interactively.

Upvotes: 1

Views: 730

Answers (1)

Donal Fellows
Donal Fellows

Reputation: 137567

If you are using the full path of the extension library in both cases, that part should work identically. It probably is doing though; if it couldn't load it, it would generate an error (which might or might not be helpful, as some of the ways that things fail give very little information; Tcl reports what it has got, but that's sometimes not enough, as it is dependent on the OS to tell it some things). Instead, the problem is probably elsewhere.

The main difference between interactive use and scripted use is that in interactive use, the unknown command will expand unknown command names to Tcl commands that the thing you typed is an unambiguous prefix of. This is convenient, but when converting to a script, you should always use the full command name. OK, not the full full command name — you mostly don't want or need the :: namespace on the front — but without abbreviation, so don't use lappe for lappend. (In interactive use, Tcl will also exec things as external programs without requiring you to type the exec explicitly; again, that's turned off in scripts as it is rather fragile.)

Could it be that this is what is going on? You can check by setting the global variable tcl_interactive to 0 before typing in your code (I recommend using cut-n-paste for that typing, so that you know exactly what is going in). If that fails, it's the interactive-mode helpfulness that is tripping you up. Check what commands you might have as an expansion for a prefix with info commands (after the load, of course):

info commands mytest*

If that just reports mytest, my theory is wrong. (Well, if it does that and the length of that string is 6; there could theoretically be extra invisible characters have been put on the command name, which would be legal Tcl but very nasty and DON'T DO THAT!)

Upvotes: 1

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