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minor adjustments

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svn: r17296
This commit is contained in:
Jon Rafkind 2009-12-14 20:18:44 +00:00
parent c2b91768cc
commit 4f4a8bc7c3
1 changed files with 5 additions and 5 deletions
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10
collects/scribblings/guide/parameterize.scrbl
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@ -6,7 +6,7 @@
@title[#:tag "parameterize"]{Dynamic Binding: @scheme[parameterize]}
@scheme[parameterize] is used to have values that are "dynamically scoped".
@scheme[parameterize] is used to have values that are ``dynamically scoped''.
You get a parameter with @scheme[make-parameter]. The parameter itself
behaves as a function: call it with no inputs and you get its value,
call it with one value and it will set the value. The settings that are
@ -25,7 +25,7 @@ For example:
(p)]
Many functions (including many primitive ones) use parameters as a way
to customize their behavior. For example @scheme[printf] will print stuff
to customize their behavior. For example @scheme[printf] will print text
using the port that is the value of the @scheme[current-output-port]
parameter. Now, say that you have some function that prints
something:
@ -63,7 +63,7 @@ you cannot solve with just globals. One is what happens when you have
multiple threads -- in this case, setting the value temporarily will
affect other threads, which may still want to print to the standard
output. Parameters solve this by having a specific value per-thread.
What happens is that each thread "inherits" the value from the thread
What happens is that each thread ``inherits'' the value from the thread
that created it, and changes in one thread are visible only in that
thread.
@ -76,10 +76,10 @@ a numeric value, and you want to do the following:
(foo)))
]
In Scheme, "tail calls" are important -- they are the basic tool for
In Scheme, ``tail calls'' are important -- they are the basic tool for
creating loops and much more. @scheme[parameterize] does some magic that
allows it to change the parameter value temporarily but still preserve
these tail calls. For example, in the above case, you *will* get an
these tail calls. For example, in the above case, you @bold{will} get an
infinite loop, rather than get a stack overflow error -- what happens
is that each of these @scheme[parameterize] expressions can somehow detect
when there's an earlier @scheme[parameterize] that no longer needs to do its