New Squeak Porting Proposals
Dean_Swan at Mitel.COM
Dean_Swan at Mitel.COM
Wed Aug 18 16:07:45 UTC 1999
From: Dean Swan at MITEL on 08/18/99 12:07 PM
>>Anybody got Squeak running on the PalmPilot yet? :)
>>
>>Craig
>>
>There's only PocketSmalltalk so far, which has a very compact binary format
>and can only develop binaries from a host PC (porting this development
>environment to the PalmPilot would be enough to make a Squeak). Anyway,
>it's basically a way to write regular apps for the Palm, but extending it
>into a full environment shouldn't be too hard, since the source is open.
>It also handles interface by augmenting the regular oo style with PalmOS
>API's.
Brian,
I don't mean to detract at all from PocketSmalltalk, because it really is
an outstanding and commendable achievement, but I wouldn't under-estimate what
it would take to turn it into a full development environment running native on a
PalmOS device.
PocketSmalltalk is not only open source, Andrew Brault and Eric Arseneau
have done a very good job of documenting it's inner workings. There are many
changes in PocketSmalltalk that would make a full blown development environment
a somewhat daunting task. Off the top of my head, these include (in no
particular order):
1) Symbols are indistinguishable from SmallIntegers at run-time.
2) PocketSmalltalk is object table based with a mark&sweep garbage
collector.
There is no generation scavenging or incremental GC in
PocketSmalltalk.
3) Classes, Methods, and (I think) Messages are not accessible as objects
at run-time.
4) Global variables are implemented as class variables of Object, and
can not be referenced as objects at run-time. The compiler
optimizes them down to inline instructions for the VM at compile time.
5) BlockContexts are not represented as objects. The restrictions are not
too bad, but they did a number of things to minimize space usage. See
the whitepaper at www.pocketsmalltalk.com for details.
PocketSmalltalk is an impressive achievment, but it is better thought of as
a traditional language compiler for producing stand-alone applications than as a
development system like Squeak. That PocketSmalltalk uses Smalltalk as it's
base language is (of course) great, but it is more of a "cross compiler" like
many
embedded systems development tools.
-Dean Swan
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