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Doc tweaks

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[SVN r1872]
This commit is contained in:
Dave Abrahams
2004-01-14 13:11:46 +00:00
parent 5d6a9c0581
commit 7c51ce7ae5
1 changed files with 20 additions and 16 deletions
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30
doc/named_params.rst
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@@ -30,10 +30,10 @@ __ ../../../index.htm
Introduction
============
In C++ function parameters are given meaning by their position in
the argument list. This protocol is fine when there are few
In C++ function arguments are given meaning by their position in
the parameter list. This protocol is fine when there are few
parameters with default values, but as the number of parameters
grows, so does the inconvenience of specifying parameters in the
grows, so does the inconvenience of passing arguments in the
correct order, especially in the presence of default values:
* It can become difficult for readers to understand the meaning of
@@ -41,8 +41,8 @@ correct order, especially in the presence of default values:
window* w = new_window("alert", true, true, false, 77, 65);
* Since meaning is given by position, we have to choose some,
often arbitrary order, for parameters with default values,
* Since meaning is given by position, we have to choose some
(often arbitrary) order for parameters with default values,
making some combinations of defaults unusable::
window* new_window(
@@ -60,9 +60,9 @@ correct order, especially in the presence of default values:
char const* name, bool border, ...
, int width = 100, int heigh = width); // error!
* Template types can not be deduced from the default values,
meaning we have to resort to overloading to provide default
values for parameters with template type::
* Template types can not be deduced from the default values, so
we have to resort to overloading to provide default values for
parameters with template type::
template<class T> void f(T x = 0);
@@ -109,16 +109,20 @@ First we define the named parameter keywords. This is done by creating
struct value_t;
namespace {
keyword<name_t> name; // keyword objects
keyword<value_t> value;
boost::keyword<name_t> name; // keyword objects
boost::keyword<value_t> value;
}
Placing these keyword objects in an unnamed namespace will prevent
link errors when you declare keywords in header files. We also
need to create a keywords list for our function::
link errors when you declare keywords in header files [**Note**:
the tag types should generally *not* be declared in an unnamed
namespace]. We also need to create a keywords list for our
function. These keywords should be declared in the same order as
their corresponding parameters appear in the function's parameter
list::
struct foo_keywords
: keywords<
: boost::keywords<
name_t
, value_t
>