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Re: Canned command sequences
From: |
Ted Stern |
Subject: |
Re: Canned command sequences |
Date: |
Fri, 20 Jun 2003 13:08:09 -0700 |
User-agent: |
Gnus/5.1003 (Gnus v5.10.3) Emacs/21.2 (usg-unix-v) |
On 20 Jun 2003, Sam Ravnborg wrote:
> Hi all.
>
> Posted the following a few weeks ago - wondered if anyone could explain it.
> I have stripped down the background info a bit - so the essense is kept.
>
<snip>
>>
>> The culprint is the extra line:
>> "echo hello again"
>> It should not be there.
Speaking only as another user ...
The essence of what you are asking is, "Why isn't the '@' indication of
no-echo respected by Make's $(call ) function and applied to the entire call?
IIUC, the answer is that you need to consider how "define/endef" differs from
a simple variable definition.
define/endef treats line endings differently -- it was specifically designed
so that you could create a function with each line written as it would be in a
target rule. When a define-function is called, those line endings mean that
each line of $(rule_up) starts a new shell process.
In other words, what the "all" target sees after $(call) is evaluated is
something like
all:
<TAB> @set -e; <TAB> echo hello
<TAB> echo hello again
Both '@' and the shell setting 'set -e' are applied only to the first shell,
so the second line of $(rule_up) is echoed.
Paul, did I get that right?
Ted
--
Ted Stern Applications Group
Cray Inc. office: 206-701-2182
411 First Avenue South, Suite 600 cell: 206-383-1049
Seattle, WA 98104-2860 FAX: 206-701-2500
Frango ut patefaciam -- I break that I may reveal
(The Paleontological Society motto, equally apropos for debugging)