[Python-ideas] "Immutable Builder" Pattern and Operator

[Soni L.]

On 22/01/17 08:54 PM, Serhiy Storchaka wrote:
> On 23.01.17 00:45, Soni L. wrote:
>> I've been thinking of an Immutable Builder pattern and an operator to go
>> with it. Since the builder would be immutable, this wouldn't work:
>>
>> long_name = mkbuilder()
>> long_name.seta(a)
>> long_name.setb(b)
>> y = long_name.build()
>
> I think the more pythonic way is:
>
> y = build(a=a, b=b)
>
> A Builder pattern is less used in Python due to the support of keyword 
> arguments.

I guess you could do something like this, for an IRC bot builder:

fnircbotbuilder = mkircbotbuilder(network="irc.freenode.net", port=6697, 
ssl=true)
mainbot = mkircbotbuilder(parent=fnircbotbuilder,  # ???
                           channels=["#bots"]).build()
fndccbotbuilder = mkircbotbuilder(parent=fnircbotbuilder, dcc=true, 
channeldcc=true)
dccbot = mkircbotbuilder(parent=fndccbotbuilder, 
channels=["#ctcp-s"]).build()
otherircbotbuilder = mkircbotbuilder(parent=fndccbotbuilder, 
network="irc.subluminal.net")  # because we want this whole network
otherbot = mkircbotbuilder(parent=otherircbotbuilder, 
channels=["#programming"]).build()    # to use DCC and channel DCC

But this would be cleaner:

botbuilder = 
mkircbotbuilder().network("irc.freenode.net").port(6697).ssl(true)
mainbot = botbuilder.channels(["#bots"]).build()
botbuilder .= dcc(true).channeldcc(true)
dccbot = botbuilder.channels(["#ctcp-s"]).build()
botbuilder .= network("irc.subluminal.net")
otherbot = botbuilder.channels(["#programming"]).build()

(I mean, "channels" could/should be a per-bot property instead of a 
per-builder property... but that doesn't affect the examples much.)