Time interpretation defaults

The time interpretation of Abjad containers initializes to either sequential or simultaneous. Defaults correspond to the most common use of each type of container. Abjad’s vanilla containers, voices and staves all default to sequential time interpretation:

Setting time interpretation at initialization

You can set the time interpretation of any container at initialization. If you know how you will use a container, go ahead and set the container’s time interpretation when you create it. The staff below initializes as simultaneous to allow two-voice polyphony:

Changing time interpretation after initialization

You can also set the time interpretation of containers after you create them. The staff below initializes as sequential. But you can change the staff’s time interpretation after you initialization:

可以在初始設定中指定進行時序，事前或事後皆可， taff.simultaneous = True。

Contexts, LilyPond type of ID:388

Working with LilyPond means understanding LilyPond contexts. Abjad implements only four concrete contexts: voice, staff, staff group, score. But LilyPond comes preloaded with 20 contexts: 9 voice contexts, 6 staff contexts, 4 staff group contexts and a score context:

也可以先初始化再更改lilypond_type ID:389

What’s an indicator? ID:390

Only a small number of musical objects carry a duration: notes, rests, chords and the tuplets, voices, staves that contain them. All the other symbols used to notate music are dependent on notes, rests, chords for their moment of performance (and their location on the page). These include articulations, fingerings, pedal markings, slurs, phrase groupings, clefs, key signatures, and many others. Abjad formalizes this idea of a non-durated object as an indicator. You attach indicators to notes, rests, chords as you compose:

指標用法 ID:391

利用迭代讓指標功能更具彈性，有趣的是聲音檔也能產生效果 D:392

許多 Abjad 物件可以轉換為 LilyPond 輸入：ID:393