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<body class='hmmessage'><div dir='ltr'>er..the proposal was old, but nevertheless..<br><br><br><br><br><div><hr id="stopSpelling">From: jay.krell@cornell.edu<br>To: hosking@cs.purdue.edu; rodney_bates@lcwb.coop<br>CC: m3devel@elegosoft.com<br>Subject: RE: [M3devel] TextLiteral.MaxBytes again<br>Date: Tue, 16 Jun 2015 08:43:10 +0000<br><br>
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<div dir="ltr">I must have missed this. I commited the "-15" solution. But this proposal sounds better. I need to revisit.. Thank you.<br><br><br><br><br><div>From: hosking@cs.purdue.edu<br>Date: Thu, 5 Sep 2013 12:05:07 -0400<br>To: rodney_bates@lcwb.coop<br>CC: m3devel@elegosoft.com<br>Subject: Re: [M3devel] TextLiteral.MaxBytes again<br><br><pre>Here is a modest proposal that should resolve this issue.<br>Declare TextLiteral.T to have a minimal buf: ARRAY [0..0] OF Byte;<br>Then use UNSAFE address arithmetic to access the bytes (TextLiteral.m3 already does the bounds checks explicitly using cnt).<br> <br>Updated TextLiteral.i3 and TextLiteral.m3 attached.<br> <br></pre><br>Antony Hosking | Associate Professor | Computer Science | Purdue University
305 N. University Street | West Lafayette | IN 47907 | USA
Mobile +1 765 427 5484
On Sep 5, 2013, at 10:42 AM, "Rodney M. Bates" wrote:
> There is another issue here. I want TextLiteral.MaxBytes to get a final size
> and not change. Every time it changes, it creates compatibility problems by
> orphaning any existing pickle files and any compiled programs that write them.
> It changes the fingerprint, so a recently-compiled reading program can't find the
> type in its own list of known types. This also affects network objects when two
> communicating programs are compiled with different TextLiteral versions.
>
> MaxBytes' particular contribution to the type doesn't otherwise matter, because it's
> artificial, but it still undermines reading pickles.
>
> I have been loading up the pickle reading code with hard-coded historical fingerprints
> of various older versions. But it's a pain to keep doing, tedious to ferret out the
> values, and it still only helps those who constantly download and compile the latest
> CM3.
>
> At some point, I am thinking of choosing some likely historical TextLiteral.T fingerprint
> and hard-coding the compiler to artificially deliver it , rather than the one computed from
> the version-of-the day of TextLiteral. But this too would not help those who would
> rather not constantly download the latest, rebuild the compiler, then recompile their
> applications.
>
> On 09/03/2013 01:02 AM, Jay K wrote:
>> ok, another question:
>>
>>
>> CONST
>> (* DIV BITSIZE should not be here! *)
>> (* MaxBytes = LAST (INTEGER) DIV BITSIZE (Byte) - 7 - 8 * ORD(BITSIZE(INTEGER) = 64); *)
>> MaxBytes = 16_7FFFFFFF DIV BITSIZE (Byte) - 7 - 8 * ORD(BITSIZE(INTEGER) = 64);
>>
>> TYPE
>> T = RTHooks.TextLiteral;
>> REVEAL
>> T = TEXT BRANDED "TextLiteral.T" OBJECT
>> cnt : INTEGER;
>> buf : ARRAY [0..MaxBytes - 1] OF Byte;
>> OVERRIDES ...
>>
>>
>> T is a reference type.
>> Is there a way to state this with no limit?
>>
>>
>> Isn't it already unsafe?
>> You know -- the array is usually smaller and the compiler is only going to check against this large size.
>>
>>
>> - Jay
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