Difference between revisions of "EPScript"
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= Data Types =
= Data Types =
== Primitive Types ==
== Primitive Types ==
Revision as of 14:43, 3 January 2007
This is an introduction.
- 1 Data Types
- 2 Operators
- 3 Functions
- 4 Examples
EPScript allows for two primitive data types (string and integer) as well as providing the means to access properties of data objects such as EPrints or Users.
Strings and characters
These are contained within either double quotes ("") or single quotes (''). There is no difference between the two, but it may be easier to use one sort when inside an XML attribute. For example:
<when test="type = 'patent'"> ... </when>
Integers are defined as a string of numbers from 0-9, e.g. 300. Leading zeros do not have any effect, and decimal values are currently not supported.
Data Objects include most of the key EPrints objects - whether an EPrint itself, documents related to the EPrint, or a user. EPScript treats all of these data objects the same, with a simple approach to retrieve properties. When an EPScript is executed, an 'item' object is supplied. In the case of a citation file, this will be the item for which the citation is being created. For a workflow, this will be the object on which the workflow acts (e.g. an EPrint or a user). Properties of main objects can be accessed using a shortened approach - the following example is from a user workflow, so the usertype property is available:
<if test="usertype = 'editor'"> ... </if>
There are cases, however, where two or more data objects may be provided - such as an EPrint and a user. Here the main item can still be accessed in the short form, but other objects use a dollar notation. In this example, the EPrint is available as $eprint:
<if test="$eprint.ispublished.one_of('unpub', 'submitted', 'inpress')"> (<print expr="$eprint.ispublished" />)</if>
Returns true if both the left-hand and the right-hand expressions return true.
<if test="type = 'book' and is_set( creators )"> ... </if>
Returns true if at least one of the expressions returns true.
<if test="type = 'book' or type = 'patent'"> ... </if>
Returns true if the expression is false and false if the expression is true.
<if test="!is_set( creators )"> ... </if>
Returns true if the left-hand expression is less than the right-hand expression. This is only applicable to expressions that return numeric values.
<if test="length(editors) lt 6"> ... </if>
Returns true if the left-hand expression is greater than the right-hand expression. This is only applicable to expressions that return numeric values.
<if test="length(editors) gt 1"> ... </if>
Returns true if the left-hand expression is equal to the right-hand expression. This applies to numeric, boolean, and string values.
<if test="type = 'patent'"> ... </if>
The inverse of the equals operator, this returns true if the expressions are not equal.
<if test="type != 'book'"> ... </if>
Functions can be called in two ways:
<when test="is_set( creators )">
These are interchangable, but it may be beneficial to use a specific form in some cases.
Returns true if the parameter is set, based on the following criteria:
- If the parameter is a string, it is set if it is not empty.
- If the parameter is a list or a complex structure, it is set if at least one value is set.
<when test="is_set( creators )"> ... </when>
Returns the number of items in the list.
<if test="length(editors) gt 1">s</if>
Returns true if the string is in the list of strings provided.
<when test="type.one_of( 'book','book_section' )"> ... </when>
Returns the reverse of a string (i.e. 'abc' becomes 'cba').
<when test="type.reverse = 'tnetap'"> ... </when>
Pluralising the editors of a book:
<if test="type = 'book' and is_set(editors)"> <print expr="editors" />, (ed<if test="length(editors) gt 1">s</if> </if>