## cppcms::base\_content |
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This is simple polymorphic class that every content for cppcms template system should be derided. It allows dynamic casting of the content to correct one for target application: |
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class base_content { |
public: |
virtual ~base_content() {}; |
}; |
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## cppcms::base\_view |
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### Members |
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- **`worker_thread &worker`** -- reference to worker thread that called rendering procedure. |
- **`ostream &cout`** -- reference to output stream that output is rendered to. |
- |
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### Derived classes: |
### How Derived Classes are created: |
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This is the class that every view generated from the template |
system is derived from. |
This is the class that every view generated from the template system is derived from. |
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For example, template: |
Every derived class defines important public member --- `content` --- the reference to user defined content class. |
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It also creates member functions for each implemented template. For example: |
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<% c++ #include "data.h" %> |
<% namespace my_view %> |
<% class message uses data::message %> |
<% template render() %> |
<html> |
<body> |
<h1><% message %> World!</h1> |
</body> |
<html> |
<% end template %> |
<% end class %> |
<% end namespace %> |
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Is rendered to C++ output: |
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#include "data.h" |
namespace my_view { |
struct message :public cppcms::base_view |
{ |
data::message &content; |
cppcms::transtext::trans const *tr; |
message(cppcms::base_view::settings _s,data::message &_content): |
cppcms::base_view(_s),content(_content) |
{ |
tr=_s.worker->domain_gettext("my_view"); |
}; |
virtual void render() { |
cout<<"\n" |
"<html>\n" |
" <body>\n" |
" <h1>"; |
cout<<escape(content.message); |
cout<<" World!</h1>\n" |
" </body>\n" |
"<html>\n" |
""; |
} // end of template render |
}; // end of class message |
} // end of namespace my_view |
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Every template class has base class it derived from -- `base_view`. This is default one. |
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Every derived class defines important public member --- reference to user defined content class. In our case: |
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data::message &content; |
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It also creates member functions for each implemented template. |
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### Member functions |
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#### Default filter |
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template<typename T> |
string escape(T const &v) |
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This is default filter, performs rendering of input parameter to text. This function is always called when template parameter is substituted without filters, i.e.: |
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<% param %> |
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is converted to |
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cout<<escape(content.param); |
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By default, it uses `ostream` to render the output, however it provides several specializations: |
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- **`string escape(string const &s)`** -- performs HTML escaping of string. |
- **`string escape(std::tm const &v)`** -- converts `std::tm` time to human readable format. |
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#### Provided Filters |
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They are called when some filters are given. Each filter has following possible signatures: |
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string filter_name(Type const &inp); |
string filter_name(Type const &inp,string param); |
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Where `inp` is given filter input and `param` is filter parameter. |
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- **`string raw(string s)`** -- raw filter, does nothing. It is used to push some html data without escaping. For example: |
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<% some_html_page | raw %> |
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- **`string intf(int val,string f)`** -- format integer number. It uses `boost::format` for this purpose. For example: |
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Decimal <% num %> is hexadecimal <% num | intf("%x"); %> |
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- **`string strftime(std::tm const &t,string f)`** -- formats output string using std::strftime call. For example: |
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<% date | strftime("%d/%m/%Y") %> |
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It has following "shortcuts" for showing, date only, time or time with seconds: |
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string date(std::tm const &t); |
string time(std::tm const &t); |
string timesec(std::tm const &t); |
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- **`string urlencode(string const &s);`** -- encode string for URL. For example: |
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<a href="http://site/article/<% link | urlencode %>"> |
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#### Other member functions |
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boost::format format(string const &f); |
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Function that returns `boost::format` object constructed with `f` and with disabled exceptions. In generally `boost::format` throw exception in case of incorrect format or parameters list --- this is not such a good behavior for displaying various data. |
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It is used mostly by gettext and ngettext implementations. For example |
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<% ngt "We have one apple","We have %1% apples",n using n %> |
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Is rendered to: |
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cout<<format(tr->gettext("We have one apple","We have %1% apples",n)) % escape(n); |
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Thus it would not throw in case of "one apple". |
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