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This page lists //JW Lua// programming topics.

===== Your First Script =====

Every programming reference seems to require a "Hello, world!" example, so here it is in //JW Lua//:
<code lua>print ("Hello, world!")</code>

===== A Quick Start ======

The fastest way to get a feel for how the //JW Lua// script language works is probably to read and test existing source code material, such as the scripts on the [[jwlua:quickscripts|example page]]. When the basics of JW Lua has been covered, there are also some larger scripts on the [[jwlua:fullscripts|page with fully-featured scripts]].

Make small changes to the script code and try and see what happens when you run it.

===== PDK Framework =====

//JW Lua// maps the Lua script language to the [[http://www.finaletips.nu/frameworkref/|PDK Framework]] (created by Jari Williamsson). For more info about how to interpret the PDK Framework documentation for scripting in //JW Lua//, please refer to [[jwlua:frameworkdocs|this page]].

All accessible PDK Framework classes starts with the ''FC'' prefix, such as ''[[http://www.finaletips.nu/frameworkref/class_f_c_measure.html|FCMeasure]]'', ''[[http://www.finaletips.nu/frameworkref/class_f_c_music_region.html|FCMusicRegion]]'', ''[[http://www.finaletips.nu/frameworkref/class_f_c_note_entry.html|FCNoteEntry]]'', etc.

The methods names (and as a result, the Lua properties) in the PDK Framework are in //CamelCase//. The constants are all-uppercase.

===== The Lua Language =====

//JW Lua// is based on Lua 5.2. More information about the Lua computer language (and books about Lua) is available at the [[http://www.lua.org/|Lua]] home page, including [[http://www.lua.org/manual/5.2/manual.html|the Lua 5.2 Reference Manual]] and the [[http://www.lua.org/pil/|On-line version of "Programming in Lua", First Edition]] (this book covers Lua 5.0, but for //JW Lua// programming purposes, it should cover what you need.)

Lua is case sensitive. The basic Lua syntax is very similar to other computer languages and Lua is an easy language to learn. To be able to write plug-in scripts there are just a few concepts in Lua you need to be aware of, such as:
  * Variables
  * Tables
  * Functions
  * Namespaces
  * ''for ... do ... end'' loops
  * ''if ... then ... end'' conditional statements

However, to really take advantage of the full power of Lua, there are other very powerful tools (such as iterators, closures and coroutines) to explore.

//JW Lua// includes all the standard Lua modules (''string'', ''math'', ''file'', etc), so they can be used in any JW Lua script, such as :
<code lua>print (math.random(1, 10))</code>
===== The 'finale' namespace =====

All functionality that accesses Finale through the Lua/PDK Framework resides within the ''finale'' namespace (namespaces use the dot separator).

For example:
<code lua>page = finale.FCPage()</code>

===== The 'finenv' namespace =====

The ''finenv'' namespace has been created to provide "programming shortcuts" to some objects that are often needed for a Finale scripts. ''finenv'' currently contains these functions:

^ Member       ^ Description     ^ 
| finenv.Region()   | Returns an object with the currently selected region (in the document/part currently in editing scope), without the need for any other method calls. | 
| finenv.UI()    | Returns the global "user interface" object (of the FCUI class). The FCUI class contains Finale and system-global tasks, such as displaying alert boxes, sounding a system beep, or getting the width of the screen, etc. | 
| finenv.UserValueInput()  | Creates and returns a dialog object to be used for [[jwlua:uservalueinput|simple user input]]. |
| finenv.FinaleVersion | A read-only property with the running Finale "year" version, such as 2011, 2012, etc. |
| finenv.RawFinaleVersion | A read-only property with the full Finale version number. It's constructed as 4 bytes with different version info. The highest byte is the major version, the next is subversion, etc. Use this only if you need the revision number of a specific major Finale version. |
| finenv.MajorVersion | A read-only property with the major version number of JW Lua. Beta versions return 0, version 1.xx gives 1, etc |
| finenv.MinorVersion | A read-only property with the minor version number of JW Lua. A version 1.07 would give 7, etc. |
| finenv.StringVersion | A read-only property with the full "printed" version number of JW Lua, as a string. |
| finenv.ConsoleIsAvailable | A read-only property that will return true if there's a console available for ''print()'' statements. Scripts that runs from the Finale menu don't have a console. Available in beta v0.28 and above. |


===== Dialog Boxes =====

//JW Lua// supports dialog boxes to the user through the finenv.UserValueInput() call. Programming of the dialog boxes is explained in full detail on [[jwlua:uservalueinput|this page]].
===== Finale Concepts =====

When you access Finale data in //JW Lua//, the data is internally handled in a way that sometimes is very different from how a Finale user experience the data. This section lists some internal concepts in Finale that a //JW Lua// programmer should be aware of.


==== Enigma Database ====

Internally, Finale stores its database, historically called //Enigma data// which is loaded/saved from/to the database. Different data record types have different access parameters. However, the PDK Framework "hides" all calls to the database through its classes and methods.

Some data (such as the "page spec" record, which describes a page with its width, height, etc) is really simple and has no linked connections to other data in the database. Other types of data demands more, and might consist of linked data records across the database (for example an expression added to the score in Finale, which contains a number of different data records).

==== TGF Entry Frame ====

Note entries however, are not accessed through Finale's usual database calls. They are accessed through a concept called the **TGF entry frame**, where all note entries in a single measure+staff+layer are accessed through one variable-sized data record. The TGF frame can actually be browsed directly in Finale, using Finale's //Edit Frame// dialog box (in the //Speedy Entry Tool//).

A note entry can contain multiple notes (which are the different pitches in a chord), but the notes are just sub-data in the note entry.


==== Optimization Flags ====

Finale makes extensive use of bit flags (access through properties in //JW Lua//) to signal that the data should behave in a certain way.

However, when connecting some data types to measures and note entries, Finale also uses some internal //flags// to mark if the database should be accessed for the specific measure/entry. These flags are optimization flags, to speed up the performance in Finale. In //JW Lua// and the PDK Framework, all optimization flags ends with ''Flag''.

Example: if a note entry has //articulations//, there's a specific optimization flag for that is accessed through the ''FCNoteEntry.ArticulationFlag'' property.

==== Editing Scope ====

Finale will edit the document and part that is currently has the **editing focus**. Technically, the editing focus might be different from what the user sees on the screen (the //visual focus//), so a script can edit data in a document/part that's not currently visible. However, as a plug-in script programmer, it's extremely important that you make sure that the editing focus and the visual focus is identical when the plug-in script ends.

===== Class Concepts ======

==== Collections ====

An important concept in the PDK Framework is the **collection**. Usually, collection classes ends with a plural 's' version of the "single-object" version. For example:
<code lua>measure = finale.FCMeasure()      -- A single measure
measures = finale.FCMeasures()    -- A collection of multiple measures </code>

Collections are not compatible with Lua tables, but they can be converted to Lua tables with the coll2table() function (see below).

==== Cells ====

A **cell** in the PDK Framework termonology is a reference to a single measure on a single specific staff. The concept is used with the ''[[http://www.finaletips.nu/frameworkref/class_f_c_cell.html|FCCell]]'' and ''[[http://www.finaletips.nu/frameworkref/class_f_c_note_entry_cell.html|FCNoteEntryCell]]'' classes, but affects other many classes as well. The coordinate system for cells (at object creation, for example) always is //x, y//, which in the cell concept means //measure_number, staff_number//.

===== Connect to Finale/JW Lua =====

To really integrate a plug-in script with //Finale// (and //JW Lua//) - so it behaves like an independent plug-in - the script can describe the script to //JW Lua// through the ''plugindef()'' function.

Please note that JW Lua can handle everything in the ''plugindef()'' function automatically, by using the //Plug-in Def// dialog box.

==== The 'plugindef()' function ====

The ''plugindef()'' function is an optional function that **only** should do a __maximum__ of 2 things:
  * Return the //plug-in name//, //undo string// and //brief description// to be used by //Finale// and //JW Lua//.
  * Define the ''finaleplugin'' namespace environment to further describe the plug-in (see below).

A simple ''plugindef()'' implementation might look like this:
<code lua>function plugindef()
    finaleplugin.RequireSelection = true
    finaleplugin.CategoryTags = "Rest, Region"
    return "Hide Rests", "Hide Rests", "Hides all rests in the selected region."
end</code>

''plugindef()'' is considered to be a reserved name in the global namespace. If the script has a function named ''plugindef()'', it might be called at any time (not only during script execution) by //JW Lua// to gather information about the plug-in. The ''plugindef()'' function can **NOT** have dependencies outside the function itself.

All aspects regarding the ''plugindef()'' execution is optional, but for a plug-in script that's going to be used repeatedly, the minimum should be to return a plug-in name, undo string and short description.

The plugindef() function can return a maximum of 3 return values (all of them should be strings):
  * The **first** return value is the //name// of the plug-in. On Windows, the ''&'' character can be used before a letter to specify that letter as a mnemonic character keystroke when the script appears in Finale's plug-in menu. //(Example: "My &Plug-in" would make ''p'' the shortcut mnemonic key.)//
  * The **second** return value is the //undo text// for the plug-in. The undo string will get a " [JW Lua]" text appended after it when Finale gets the undo record.
  * The **third** return value is a //brief description text// (for the status/message bar in //Finale// and the //JW Lua// user interface).

Again, all these return values are optional.

==== The 'finaleplugin' namespace ====

The ''finaleplugin'' namespace is a reserved and defined namespace for the ''plugindef()'' execution. It can both contain properties that affect how the script will run and properties that further describes the script to the outside world.

Please note that since the execution of ''plugindef()'' is completely silent (no errors are displayed on failure), make absolute sure that all spellings are correct (including correct upper/lower case).

The ''finaleplugin'' properties should **only** be set in the ''plugindef()'' function.

The properties are discussed in details on the [[jwlua:finaleplugin_properties|finaleplugin properties]] page.
===== print() Redirection =====

The output of the standard Lua ''print'' function has been redirected to the //JW Lua// window, so all output from the ''print'' function will show up there:

{{:wiki:jwlua:jwlua_beta0_01-print.png|}}

===== Additional JW Lua Functions =====

//JW Lua// adds some some functions to the global namespace that are specially designed for plug-in script programming. They are listed below:

==== coll2table() ====

''coll2table()'' transforms a PDK Framework collection object into a Lua-style table, so the items can be used with the Lua standard functions for tables (such as the standard ''table.'' library). The resulting table is 1-based (not 0-based as the PDK Framework collections). For example:

<code lua>-- Load all measure objects
allmeasures = finale.FCMeasures()
allmeasures:LoadAll()
-- Convert to table
measuretable = coll2table(allmeasures)
-- Sort the measure objects according to their width (widest measure first)
table.sort(measuretable, function (a,b) return (a.Width > b.Width) end)
-- Print the sorted result
for i, v in ipairs(measuretable) do
   print ("Item", i, "is measure number", v.ItemNo, "with the width", v.Width)
end</code>

==== dumpproperties() ====

''dumpproperties()'' creates a table consisting of all available properties for an object and their values. The keys in the table is the property names; the values in the table are the property values. Use the ''pairsbykeys()'' iterator (see below) to get the properties sorted in alphabetical order.

<code lua>page = finale.FCPage()
page:Load(1)
properties = dumpproperties(page)
for k, v in pairsbykeys(properties) do
   print (k, "=", v)
end</code>
==== each() ====

''each()'' is the general iterator "factory" for PDK Framework collection objects. It feeds the ''for'' loop with all the elements of the collection:

<code lua>-- Print the widths for all the pages
allpages = finale.FCPages()
allpages:LoadAll()
for v in each(allpages) do
     print ("Page", v.ItemNo, "has the width", v.Width)
end</code>

==== eachentry() ====

''eachentry()'' feeds a ''for'' loop with all the note entry objects in a region, without saving them back.

First parameter to this function is the region to process, where you could use ''finenv.Region()'' to get the current selection.

The second parameter is optional, but can be used to indicate the note entry layer(s) to load in Finale. The default is to load all visible layers. These values are available:
^  Value     ^   Description   ^
| -3         | Don't load any entries. |
| -2         | The non-visible layers(s). |
| -1         | All layers, regardless if they're visible or not. |
| 0          | All visible layer(s). This is the default.         |
| 1 through 4 | Load only the one-based layer number. The layer is loaded regardless of the layer visibility. |
| A bit mask combination of hex values 0x100, 0x200, 0x400, 0x800 | The layers 1-4 in any combination. |

Example:
<code lua>counter = 0
for e in eachentry(finenv.Region()) do
   if e:IsRest() then
      counter = counter + 1
   end
end
print ("The region contains", counter, "rest entries.")</code>

==== eachentrysaved() ====

''eachentrysaved()'' feeds a ''for'' loop with all the note entry objects in a region and automatically saves the entries back to Finale after processing. Only use this function when the entries actually needs to be saved. It requires the same parameter(s) as ''eachentry()'' (see above).

One other task that can be automatically done with ''eachentrysaved()'' is to delete entries. Just set the duration to 0, and ''eachentrysaved()'' will automatically delete the entry prior to saving it.

<code lua>-- Let eachentrysaved() delete all rests in the selected region
for e in eachentrysaved(finenv.Region()) do
   if e:IsRest() then e.Duration = 0  end
end</code>

Due to the way the TGF frame works, the note entry is not saved directly after each loop turn, but only when a frame has been fully processed.

==== eachcell() ====

''eachcell()'' feeds a ''for'' loop with all the cell coordinates for a region. Partially selected measures are treated as being selected. The first coordinate is the measure, the second is the staff ID. ''eachcell()'' requires a region as the parameter, the easiest way is to refer to ''finenv.Region()'' to get the currently selected region.

Example:
<code lua>for m, s in eachcell(finenv.Region()) do
   print ("Measure: ", m, "Staff: ", s)
end</code>

==== loadall() ===

''loadall()'' feeds a ''for'' loop with the elements from a collection, typically where the data hasn't been loaded. The supplied collection must support the ''LoadAll()'' method. This is a useful shortcut when the collection itself isn't important, but rather all the items in the collection.

Example:
<code lua>for m in loadall(finale.FCMeasures()) do
   print ("Measure width: ", m.Width)
end</code>

==== loadallforregion() ===

''loadallforregion()'' feeds a ''for'' loop with the elements from a collection, based on a region. The first argument is a created collection, typically without any loaded objects. The second argument is the region.

The supplied collection must support the ''LoadAllForRegion()'' method. This is a useful shortcut when the collection itself isn't important, but rather all the items in the collection.

Example:
<code lua>local region = finenv.Region()
for e in loadallforregion(finale.FCExpressions(), region) do
   print ("Expression's measure:", e.Measure)
end</code>

==== pairsbykeys() ====

''pairsbykeys()'' feeds a ''for'' loop with the table elements, where the elements appear sorted by key. It returns the key/value pair just like //Lua//'s own ''pairs()'' iterator.

Example:
<code lua>t = {}
t["test"] = 12
t["a test"] = 100
for k, v in pairsbykeys(t) do
   print (k, "=", v)
end</code>
===== Memory Management =====

The Lua language handles memory through a garbage collection: the memory are handled automatically by Lua. However, there are a couple of points that a plug-in programmer should be aware of.

  * Define variables as ''local'' as often as possible. This becomes particularly important when group scripts are used (global variables survives to the subsequent scripts in the group as well), or when using libraries.
  * The memory allocated by JW Lua's ''Create'' methods are handled automatically by JW Lua (and not by the Lua interpreter) and those memory objects are released __after__ the full script has been run.
  * Since the ''Create'' methods could sometimes result in a huge number of object waiting for release (for example in a tight loop), ''Lookup'' classes (classes that ends with ''Lookup'') are available as a faster and more memory-efficient approach.
  * When using the ''FCCellMetrics'' or ''FCNoteEntryMetrics'' class, make sure to call the ''FreeMetrics()'' method separately for the loaded object as soon as the data is no longer is needed. Finale allocate loaded metrics data internally, and metrics with a garbage collector can otherwise lead to problems in scripts where lots of metrics data are loaded without release.

===== Tips =====

  * If you don't need a collection object anymore, you can set it to ''nil''. That might benefit the performance in large scripts with huge collections of data (since it signals to the garbage collector that it can free the allocated memory).
  * There's virtually no performance penalty to put lots of comments in the script code. Once the script has been loaded into the Lua engine, the code resides in (quite efficient) bytecode where only the actual execution code appears.
  * An alternative syntax for properties is to use the property name as a string table index with the object as a table. For example, the syntax ''mymeasure.Width'' is equivalent to ''mymeasure["Width"]''. This alternative syntax might be useful when referencing properties dynamically through the code.
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