Wiki Talk Expression

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Summary

Expressions are the key syntactic building block of WikiTalk.

Basic Definition

An expression can be:

• a literal (a string, number, collection or block)
• a reference to a variable
• a reference to a member (property or method) of an object

Examples

Here are some examples:

100	A number
"hello"	A string
DateTime.Now	A member (property) reference
topic.Title	The name of the current topic

More Details

Literals

A literal is a number, a string, a collection or a block.

Here are some examples:

100	A number
-20	A negative number
"hello"	A string
[100, 200, 300]	A collection with three elements
{topic.LastModifiedBy}	A block literal (see WikiTalkBlock)

Question

What is the syntax for a literal string that contains double quotation marks?

Answer

Use a backslash for an escape, for example

 "He said \"How are you?\""

Unqualified references

An unqualified reference is a reference, by name, to a variable (that is in scope). This could be either a WikiTalkWellKnownObject, a BlockParameter or a member of an object that has been brought into scope using the WithFunction.

Here are some examples:

topic	A reference to the variable called topic
topics	A reference to the variable called topics
myTemporaryVariable	A reference to the variable called myTemporaryVariable

Qualified references

A qualified reference is a reference to a member (property or function) of some object.

Here are some examples:

DateTime.Now	The current date and time (the Now property of the DateTime object)
someString.Length	The length of the given string
"hello".Length	The length of the given string (in this case, 5)
"hello".SubString(0,2)	The first 2 character of the word hello: he
"hello".SubString(0,2).Length	The length of the first 2 character of the word hello; i.e., 2