From mboxrd@z Thu Jan  1 00:00:00 1970
To: 9fans@cse.psu.edu
Subject: Re: [9fans] troff ignoring .eo/.ec after first time
From: "Russ Cox" <rsc@swtch.com>
Date: Thu, 22 Nov 2007 11:55:10 -0500
In-Reply-To: <3950E912-6C70-4726-B16D-79008B73FE00@mac.com>
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> On about the third page, some code begins, but at the print()  
> statement at the end there is some strangeness. If you look inside  
> the .ms file, there are some .eo and .ec requests. .eo turns off \x  
> and .ec turns it back on. But why is it ignored after that first  
> page, which works correctly?

assuming that /n/sourcesdump/2007/1122/contrib/pietro/plan9prog.ms
is the file in question, the first page isn't "working" correctly either,
since your

	print("hello, world\n");

turns into

	print("hello, world0);

because the \n" interpolates the " register.

the reason that .eo doesn't manage to turn this off is that
the text between .P1 and .P2 gets copied into a troff 
diversion for later processing, and that later processing
happens during the execution of .P2, by which time your idiom

	.P1
	.eo
	text
	.ec
	.P2

has restored \ as the escape character.

you can get your desired effect by doing

	.P1
	.eo
	text
	.P2
	.ec

instead.

russ