Python >>> Transcript Translation

[Alex Tweedly]

At 18:14 18/12/2004 -0500, Troy Rollins wrote:


>On Dec 18, 2004, at 2:35 PM, Roger.E.Eller at sealedair.com wrote:
>
>>Can anyone out there who is familiar with Python please translate the
>>script below to Transcript? This script is supposed to be able to create a
>>Hard-Drive image that works with the PearPC Macintosh Emulator. I want a
>>native Rev script that can create this multi-gigabyte file.
>
>But... that script is importing and using a separate object (script 
>instantiation) called "sys" which is actually doing all the work.

Well, not really "all the work". The "sys" import is only used to extract 
the command line arguments.

>Even with access to that, I don't have any idea if Transcript can actually 
>achieve *all* the same things Python can... Python is tied into OSX at the 
>system level.

Python uses standard system libraries - not all of which Rev lets you 
access; but in this case, there shouldn't be any problem.

Let's get the arguments from an input field, instead of a command line 
argument ...

>#!/usr/bin/python
># Copyright (c) 2004 Marco Lange.
>
>
>import sys
>
>
>GRANULARITY = 516096
>
>
>imagename = sys.argv[1]
>imagesize = int(sys.argv[2])
>if imagesize % GRANULARITY != 0:
>    imagesize = ((imagesize / GRANULARITY) + 1) * GRANULARITY
>
>
>print "Using image size:", imagesize

Simply gets a file name and a value; takes the value, and rounds (up) to a 
multiple of granularity.

local GRANULARITY = 516096
put field "inputField" into myVar
if myVar mod GRANULARITY <> 0 then
   put GRANULARITY * (trunc(myVar/Granularity)+1) into myVar
end if

>imagefile = open(imagename, "wb+")
>imagefile.seek(imagesize-1)
>imagefile.write("\x00")
>imagefile.close

Open the file named earlier for binary write (overwriting any existing 
content), seeks to the byte position (from the value above), writes one 
null byte and closes the file. (i.e. creates a large, empty file)

ask file "File to write" .....
put it into myFileName
open file myFileName for binary write
seek to myVar in file myFileName
write numtochar(0) to file myFileName
close file myFileName


NB - not tested, but allowing for any typos, that should do it.
There's perhaps an "off by one" error - because Python numbers bytes from 
zero, and Rev from 1 - so the seek should maybe be to "myVar-1".

-- Alex.