Differences

This shows you the differences between two versions of the page.

--- syntax:start [2017/12/23 09:55] – dmitry
+++ syntax:start [2025/06/24 00:18] (current) – dmitry
@@ Line 1: / Line 1: @@
 ====== Expressions ======
-In EasyMorph you can use expressions to [[transformations:addcolumn|calculate new columns]] or build complex conditions for [[transformations:filter|filtering table rows]]. An expression is calculated for every row of a table and can include:
+In EasyMorph, you can use expressions to [[transformations:addcolumn|calculate new columns]] or build complex conditions for [[transformations:filter|filtering table rows]]. An expression is calculated for every row of a table and can include:
   * Numbers and text strings (see [[syntax:types|Type system]])
@@ Line 9: / Line 9: @@
 === Field names ===
-You can refer to values in columns of the table where the expression is calculated by putting column names in square brackets, e.g. [Amount]. Field names can include spaces, digits and non-alphabetical characters in any order.
+You can refer to values in columns of the table where the expression is calculated by putting column names in square brackets, e.g. [Amount]. Field names can include spaces, digits, and non-alphabetical characters in any order.
 When expression is calculated for a row, field names are replaced with values in these fields stored in the row. It's not possible to refer to values from another row or another table.
-Field names are case sensitive -- i.e. [Total], [TOTAL] and [total] are 3 different field names.
+Field names are case sensitive -- i.e. [Total], [TOTAL], and [total] are 3 different field names.
 === Parameters ===
 An expression can refer to [[parameters:|project parameters]] that are evaluated to text or number constants prior to calculating the expression. Parameter names in expressions are wrapped in curly brackets and are case-sensitive. E.g. {File name}, {Ratio}.
+=== Comments ===
+Expressions can be annotated (commented). Any text between a double-slash (%%//%%) and the end of line is considered a comment and is ignored during expression evaluation. A comment can't span several lines. Example:
+<code>
+//Converted amount.
+[Amount] * {FX Rate}  // Using a parameter for the exchange rate.
+</code>
 === Example 1 ===
-Let's assume we want to calculate new field 'Net Amount' using the following expression:
+Let's assume we want to calculate a new field 'Net Amount' using the following expression:
   [Price] * [Quantity] * ( 100 - [Discount %] ) / 100
@@ Line 33: / Line 42: @@
 === Example 2 ===
-Let's assume we want to calculate new field 'Total Tax' using the following expression:
+Let's assume we want to calculate a new field 'Total Tax' using the following expression:
   [Amount] * if( [Province]='QC', 13.5, 12.5) / 100 * {Multiplier}
@@ Line 46: / Line 55: @@
-=== A few transformations that use expressions ===
+=== A few actions that use expressions ===
   * [[transformations:addcolumn|Calculate new columns]]
-  * [[transformations:replacecolumn|Calculate and replace columns]]
+  * [[transformations:replacecolumns|Calculate and replace columns]]
   * [[transformations:rule|Rule]]
   * [[transformations:filter|Filter by condition]]
   * [[transformations:trimbycondition|Trim by condition]]
   * [[transformations:halt|Halt on condition]]
+=== Generating expressions from description ===
+Starting from v5.9.6, it's possible to generate an expression from a description in plain English. To learn more, read [[syntax:generate|How to describe expressions]].