Editing Namespace (section)

===Emulating namespaces===
In programming languages lacking language support for namespaces, namespaces can be emulated to some extent by using an [[identifier naming convention]]. For example, [[C (programming language)|C]] libraries such as [[libpng]] often use a fixed prefix for all functions and variables that are part of their exposed interface. Libpng exposes identifiers such as:

 png_create_write_struct
 png_get_signature
 png_read_row
 png_set_invalid

This [[naming conventions (programming)|naming convention]] provides reasonable assurance that the [[identifier]]s are unique and can therefore be used in larger programs without [[naming collision]]s.<ref>{{Cite web|url=http://www.informit.com/guides/content.aspx?g=cplusplus&seqNum=286 |title=Why I Hate Namespaces |author=Danny Kalev |url-status=bot: unknown |archive-url=https://web.archive.org/web/20160709115609/http://www.informit.com/guides/content.aspx?g=cplusplus&seqNum=286 |archive-date=2016-07-09 }}</ref> Likewise, many packages originally written in [[Fortran]] (e.g., [[BLAS]], [[LAPACK]]) reserve the first few letters of a function's name to indicate the group to which the function belongs.

This technique has several drawbacks:
* It doesn't scale well to nested namespaces; identifiers become excessively long since all uses of the identifiers must be [[fully qualified name|fully namespace-qualified]];
* Individuals or organizations may use inconsistent naming conventions, potentially introducing unwanted obfuscation;
* Compound or "query-based" operations on groups of identifiers, based on the namespaces in which they are declared, are rendered unwieldy or unfeasible;
* In languages with restricted identifier length, the use of prefixes limits the number of characters that can be used to identify what the function does; this is a particular problem for packages originally written in [[Fortran|FORTRAN 77]], which offered only 6 characters per identifier; for example, the name of the [[BLAS]] function <code>DGEMM</code> indicates that it operates on double-precision floating-point numbers (<code>D</code>) and general matrices (<code>GE</code>), with only the last two characters (<code>MM</code>) showing what it actually does: matrix–matrix multiplication.

It also has a few advantages:
* No special software tools are required to locate names in source-code files; a simple program like [[grep]] suffices;
* There are no namespace-related name conflicts;
* There is no need for name mangling, and thus no potential incompatibility problems.