PHP File Formatting
Maximum Line Length
PHP Code Demarcation
Numerically Indexed Arrays
Class Member Variables
Functions and Methods
Function and Method Declaration
Function and Method Usage
Exception when IF only returns something
All new functions created in ImpressCMS core will have the following prefix : "icms_"
All classes created in ImpressCMS will be prefixed with "Icms"
Also, the file holding this class will also be prefixed with "icms"
The basis of the ImpressCMS coding standards are the standards used by Zend Framework, which are also based on the PEAR coding standards. However, we differ in a few ways with Zend standards. Our standards are defined below.
For files that contain only PHP code, the closing tag ("?>") at the end of the file is never permitted. It is not required by PHP, and omitting it prevents the accidental injection of trailing white space into the response.
The target line length is 100 characters. That is to say, ImpressCMS developers should strive keep each line of their code under 100 characters where possible and practical. However, longer lines are acceptable in some circumstances.
Line termination follows the Unix text file convention. Lines must end with a single linefeed (LF) character. Linefeed characters are represented as ordinal 10, or hexadecimal 0x0A.
Note: Do not use carriage returns (CR) as is the convention in Apple OS's (0x0D) or the carriage return - linefeed combination (CRLF) as is standard for the Windows OS (0x0D, 0x0A).
PHP code must always be delimited by the full-form, standard PHP tags:
Short tags are never allowed. For files containing only PHP code, the closing tag must always be omitted
The "double quotes" should always be used to demarcate the string:
Variable substitution is permitted using either of these forms:
For consistency, this form is not permitted:
Strings must be concatenated using the "." operator. A space must always be added before and after the "." operator to improve readability:
When concatenating strings with the "." operator, it is encouraged to break the statement into multiple lines to improve readability. In these cases, each successive line should be padded with white space such that the "."; operator is aligned under the "=" operator:
Negative numbers are not permitted as indices.
An indexed array may start with any non-negative number, however all base indices besides 0 are discouraged.
When declaring indexed arrays with the Array function the following form is mandatory
When declaring associative arrays with the Array construct, breaking the statement into multiple lines is mandatory. In this case, each successive line must be padded with white space such that both the keys and the values are aligned:
Classes must be named according to ImpressCMS naming conventions.
The opening curlybrace is to be placed on the same line, and the ending curlybrace on his own line.Every class must have a documentation block that conforms to the PHPDocumentor standard.
Only one class is permitted in each PHP file.
Placing additional code in class files is permitted but discouraged. In such files, two blank lines must separate the class from any additional PHP code in the class file.
The following is an example of an acceptable class declaration:
Classes that extend other classes or which implement interfaces should declare their dependencies on the same line when possible.
If as a result of such declarations, the line length exceeds the maximum line length, break the line before the "extends" and/or "implements" keywords, and pad those lines by one indentation level.
If the class implements multiple interfaces and the declaration exceeds the maximum line length, break after each comma separating the interfaces, and indent the interface names such that they align.
Member variables must be named according to ImpressCMS variable naming conventions.
Any variables declared in a class must be listed at the top of the class, above the declaration of any methods.
The var construct is not permitted. Member variables always declare their visibility by using one of the private, protected, or public modifiers. Giving access to member variables directly by declaring them as public is permitted but discouraged in favor of accessor methods (set & get).
Functions must be named according to ImpressCMS function naming conventions.
Methods inside classes must always declare their visibility by using one of the private, protected, or public modifiers.
Space between the function name and the opening parenthesis for the arguments is not permitted.
Functions in the global scope are strongly discouraged.
The following is an example of an acceptable function declaration in a class:
In cases where the argument list exceeds the maximum line length, you may introduce line breaks. Additional arguments to the function or method must be indented one additional level beyond the function or method declaration. A line break should then occur before the closing argument paren, which should then be placed on the same line as the opening brace of the function or method with one space separating the two, and at the same indentation level as the function or method declaration. The following is an example of one such situation:
Call-time pass-by-reference is strictly prohibited.
The return value must not be enclosed in parentheses. This can hinder readability, in additional to breaking code if a method is later changed to return by reference.
Function arguments should be separated by a single trailing space after the comma delimiter. The following is an example of an acceptable invocation of a function that takes three arguments:
Call-time pass-by-reference is strictly prohibited. See the function declarations section for the proper way to pass function arguments by-reference.
In passing arrays as arguments to a function, the function call may include the "array" hint and may be split into multiple lines to improve readability. In such cases, the normal guidelines for writing arrays still apply:
Control statements based on the if and elseif constructs must have a single space before the opening parenthesis of the conditional and a single space after the closing parenthesis.
Within the conditional statements between the parentheses, operators must be separated by spaces for readability. Inner parentheses are encouraged to improve logical grouping for larger conditional expressions.
The opening brace is written on the same line as the conditional statement. The closing brace is always written on its own line. Any content within the braces must be indented using four spaces.
If the conditional statement causes the line length to exceed the maximum line length and has several clauses, you may break the conditional into multiple lines. In such a case, break the line prior to a logic operator, and pad the line such that it aligns under the first character of the conditional clause. The closing paren in the conditional will then be placed on a line with the opening brace, with one space separating the two, at an indentation level equivalent to the opening control statement.
The intention of this latter declaration format is to prevent issues when adding or removing clauses from the conditional during later revisions.
For "if" statements that include "elseif" or "else", the formatting conventions are similar to the "if" construct. The following examples demonstrate proper formatting for "if" statements with "else" and/or "elseif" constructs:
PHP allows statements to be written without braces in some circumstances. This coding standard makes no differentiation- all "if", "elseif" or "else" statements must use braces.
Exception when IF only returns something
When an IF statement only returns something, it is allowed to write it on a single line:
Control statements written with the "switch" statement must have a single space before the opening parenthesis of the conditional statement and after the closing parenthesis.
All content within the "switch" statement must be indented using four spaces. Content under each "case" statement must be indented using an additional four spaces.
The construct default should never be omitted from a switch statement.
Note: Note: It is sometimes useful to write a case statement which falls through to the next case by not including a break or return within that case. To distinguish these cases from bugs, any case statement where break or return are omitted should contain a comment indicating that the break was intentionally omitted.