Re: rfc 2045 base64 encoding/decoding module

[Valentin Kamyshenko <val at kamysh dot materials dot kiev dot ua>]

>>>>> "sen" == sen ml <sen_ml@eccosys.com> writes:

sen> once i'm done w/ that, i'm hoping to work on the pack/unpack
sen> thing.  i'm much more familiar w/ the perl version than the
sen> python one though so what i make may end up more perlish than
sen> pythonish (at least at first).

My suggestion would be to separate reading/writing binary data and
forming the perl/python-like structures.
Namely, I would make a separate module

(define-module (utils binary-io))

(export 
	;; native format
	read-int read-short read-long 
	read-unsigned read-ushort read-ulong

	;; fixed precision
	read-int16 read-unsigned16
	read-int32 read-unsigned32
	
	;; variants with different "endiands"
	read-int16/big-endian read-unsigned16/big-endian
	read-int16/little-endian read-unsigned16/little-endian
	read-int32/big-endian read-unsigned32/big-endian
	read-int32/little-endian read-unsigned32/little-endian

	;; floats
	read-float read-double)

(export 
	;; native format
	write-int write-short write-long 
	write-unsigned write-ushort write-ulong

	;; fixed precision
	write-int16 write-unsigned16
	write-int32 write-unsigned32
	
	;; variants with different "endiands"
	write-int16/big-endian write-unsigned16/big-endian
	write-int16/little-endian write-unsigned16/little-endian
	write-int32/big-endian write-unsigned32/big-endian
	write-int32/little-endian write-unsigned32/little-endian

	;; floats
	write-float write-double)

Of course, all these functions should read/write to/from ports.

Then, on the base of these functions, the perl-like and/or python-like 
struct modules could be written.
I'm not sure, how it works with perl, but with python you generate
(by default) the actual C structure (represented as string), with the
proper alignment of components.
For example:

>>> import struct
>>> struct.pack("ch","A",2)
'A\000\002\000'
>>> struct.pack("cf","A",2)
'A\000\000\000\000\000\000@'

But you can switch off this behavior:
>>> struct.pack("=ch","A",2)
'A\002\000'
>>> struct.pack("=cf","A",2)
'A\000\000\000@'

Also, you can require big-endian/little-endian representation for
the whole string:
>>> struct.pack(">ch","A",2)
'A\000\002'
>>> struct.pack("<ch","A",2)
'A\002\000'
>>> struct.pack(">cf","A",2)
'A@\000\000\000'
>>> struct.pack("<cf","A",2)
'A\000\000\000@'


sen>                                 i have the same question
sen> regarding whether the routines should operate on ports as
sen> compared to strings.  any opinions?
With ports, it seems to be more flexible.

--
Best regards,
	Valentin.