[erlang-questions] module reloading

[Alex Alvarez]

Thanks for your reply!  I can certainly understand that and appreciate
the system would be letting me know if I was trying to do that.  But
the issue is that I was not trying to load any code of mine with the 
same module name, I just tried reloading the same (e.g., math) module.

Erlang/OTP 20 [erts-9.3] [source] [64-bit] [smp:2:2] [ds:2:2:10]
[async-threads:10] [hipe] [kernel-poll:false]

Eshell V9.3  (abort with ^G)
1> l(math).
{module,math}
2> l(math).
{error,sticky_directory}
3> 
=ERROR REPORT==== 15-Apr-2018::22:09:00 ===
Can't load module 'math' that resides in sticky dir

As mentioned in my last email, the issue seems to be with the fact
that the module was not marked old...

3> code:purge(math).
false

Now, I just thought that c:l() would load and reload any module
regardless, but that doesn't seem to be the case.

http://erlang.org/doc/man/c.html#l-1
http://erlang.org/doc/man/code.html#purge-1

Thanks,
Alex
On 4/13/2018 at 4:26 PM, "Joe Armstrong"  wrote:The module called
'math' is a pre-defined system module, and
redefining it might have
unpleasant and unpredictable consequences - so you really should not
do this unless you
know exactly what you are doing. Best is to just change the name.

If you know what you're doing you can call unstick_dir on the
directory where math.beam was loaded from
and then you will be able to change the code - again this is not a
good idea if you don't
really understand the consequences of doing this.

System modules are 'sticky' by default to stop you from accidentally
shooting yourself in the foot.

If you get this warning just change the module name.

Cheers

/Joe

On Fri, Apr 13, 2018 at 7:13 PM, Alex Alvarez  wrote:
> Sorry if this was already asked and I missed it...  While using
v20.3.2,
> after I load a module...
>
> 11> l(math).
> {module,math}
>
> ...if I try to reload it again with the same command...
>
> 12> l(math).
>
> =ERROR REPORT==== 13-Apr-2018::13:09:15 ===
> Can't load module 'math' that resides in sticky dir
> {error,sticky_directory}
>
> ...I get this error message. It's not particular to any module. 
>From the
> error, there seems to be a problem with a stcky bit somewhere. 
Although I
> don't remember having this problem before, who knows, maybe it's
just my
> install.  Has anyone run into this issue recently?
>
> Thanks,
> Alex
>
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