why does the process dictionary have a bad rep?

ke.han <>
Fri Jul 15 17:18:22 CEST 2005

This thread is talking about two things: abuse of the proc dict and 
abuse of message passing.
I understand the example of using the proc dict to get around single 
assignment.  You guys have lost me on the second part.
Can someone give an example of message passing abuse?  What does message 
passing have to do with variable assignment?
thanks, ke han

Ulf Wiger wrote:
> Den 2005-07-15 11:09:36 skrev Matthias Lang <>:
>> Valentin Micic writes:
>> [about the process dictionary]
>>  > has to reply with message. What are the limitations of dictionary,  
>> and *why*
>>  > it received a bad reputation?
>> In addition to the points already made, another reason is that a
>> significant proportion of those who haven't seen single-assignment
>> before will seize upon anything which "finally lets me assign to a
>> damn variable like I want to", and the first 'anything' they usually
>> encounter is the process dictionary.
>> (ab)using processes and message passing to achieve the same effect at
>> least has the side effect of teaching them about message passing.
> Agreed. The problem isn't that we shouldn't caution about use
> of the process dictionary. We should do so in a way that people
> get a chance to learn why it should be used with care, and what
> else should be used with care.
> I have yet to find the chapter that explains this.
> Erlang has a pragmatic approach to message passing (no monads,
> etc.) This is wonderful in many ways, but it also introduces
> some juicy opportunities to write terrible code.
> /Uffe

More information about the erlang-questions mailing list