Common Functionality

Common Functionality in openLilyLib

Activating openLilyLib automatically loads some common functionality which is then available for anybody, be it document authors or library developers. This page and its sub-pages provide a reference to this part of openLilyLib.

Option Handling

openLilyLib provides a unified interface to option and configuration handling that can be used by document authors too. Read more on Option-Handling.

Logging Functionality

openLilyLib provides a unified interface to provide logging information. Read more on Logging.

Miscellaneous Functionality

openLilyLib implements or loads functionality that is needed for it to work properly. All of this functionality is of course available for any document author or library developer too.

General Predicates

Often developers locally define predicates to be used by their functions. openLilyLib encourages them to consider adding them to the global collection of predicates - in order to reduce redundancy in the code.

Available predicates in openLilyLib are:

• stringlist?
  returns #t if the argument is a list and all of its elements are strings
• string-or-alist?
  returns #t if the argument is either a string or a list of pairs.

LilyPond version predicates

Version predicates can be used to conditionally execute code based on the LilyPond version that is currently compiling the document. This makes it possible to write code that can be compiled with different LilyPond versions even when there are breaking syntax changes in between. For individual users this may seem unnecessary but it can become a life-saver if you collaborate with others or if you provide a library and don't want to prescribe a certain (usually: minimal) LilyPond version to your users. The available predicates are:

• lilypond-greater-than?
• lilypond-greater-than-or-equal?
• lilypond-less-than?
• lilypond-less-than-or-equal?
• lilypond-equals?.

The LilyPond version to be compared agains can be passed either a version string or as a list of three integers, like

#(if (lilypond-greater-than? "2.19.7") #t #f)
#(if (lilypond-less-than? '(2 19 6) #t #f)

Path Handling

The os-path Scheme module provides a number of functions to deal with file paths in an OS independent way, similar to Python's os.path module. It provides numerous functions that may be useful for document authors as well. Read more on Path-Handling.

Support for Association Lists

Association lists are a very common data structure when working with LilyPond, and openLilyLib makes heavy use of them for its option handling. Therefore a number of helper commands are available. Read more on Association-List-Support.

Miscellaneous Tools

• \includePattern
  TODO: CHECK IF THIS REALLY WORKS