5.1 Language Constructs

5.1 Language Constructs - Summary

Comments and documentation strings
1. ## single line
2. #* multi line *#
Generation, caching and filtering of output
1. plain text
2. look up a value: $placeholder
3. evaluate an expression: #echo ...
4. same but discard the output: #silent ...
5. one-line if: #if EXPR then EXPR else EXPR
6. gobble the EOL: #slurp
7. parsed file includes: #include ...
8. raw file includes: #include raw ...
9. verbatim output of Cheetah code: #raw ...#end raw
10. cached placeholders: $*var, $*<interval>*var
11. cached regions: #cache ...#end cache
12. set the output filter: #filter ...
13. control output indentation: #indent ...(not implemented yet)
Importing Python modules and objects: #import ..., #from ...
Inheritance
1. set the base class to inherit from: #extends
2. set the name of the main method to implement: #implements ...
Compile-time declaration
1. define class attributes: #attr ...
2. define class methods: #def ...#end def
3. #block ...#end block provides a simplified interface to #def ...#end def
Run-time assignment
1. local vars: #set ...
2. global vars: #set global ...
3. deleting local vars: #del ...
Flow control
1. #if ...#else ...#else if (aka #elif) ...#end if
2. #unless ...#end unless
3. #for ...#end for
4. #repeat ...#end repeat
5. #while ...#end while
6. #break
7. #continue
8. #pass
9. #stop
error/exception handling
1. #assert
2. #raise
3. #try ...#except ...#else ... #end try
4. #try ...#finally ...#end try
5. #errorCatcher ...set a handler for exceptions raised by $placeholder calls.
Instructions to the parser/compiler
1. #breakpoint
2. #compiler-settings ...#end compiler-settings
Escape to pure Python code
1. evalute expression and print the output: <%= ... %>
2. execute code and discard output: <% ...%>
Fine control over Cheetah-generated Python modules
1. set the source code encoding of compiled template modules: #encoding
2. set the sh-bang line of compiled template modules: #shBang

The use of all these constructs will be covered in the next several chapters.