January 2018
Intermediate to advanced
856 pages
17h 17m
Chinese
Content preview from Python 技術手冊 第三版
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產生 HTML
|
699
jinja2.Environment 類別
當你使用
jinja2
，永遠都會涉及一個
Environment
實體，在少數情況中，你
可以讓它預設為一個通用的「共用環境（shared environment）」，但並不建
議那樣做。只有在非常進階的用法中，你會從不同的來源取得範本（或使
用不同的範本語言語法）時，你才會定義多個環境，通常，你會實體化單
一個
Environment
實體
env
，適用於你需要處理的所有範本。
你能在建置的時候以許多方式自訂
env
，方法是將具名引數傳入它的建構
器（包括更動範本語言語法的關鍵面向，例如哪些分隔符號起始和結束區
塊、變數、註解等等），但在真實世界的用例中，你幾乎永遠都會傳入的
一個具名引數是
loader=...
。
一個環境的
loader
指出從何處載入範本，在被請求的時候：通常是檔案系
統中的某個目錄，又或者是某個資料庫（對於後者，你必須編寫
jinja2.
Loader
的一個自訂的子類別），但還有其他的可能性。你需要一個載入
器（loader）來讓範本享有
jinja2
的某些強大的功能，例如
範本繼承
（
template inheritance
，本書中並沒有涵蓋）。
實體化的時候，你可用自訂的過濾器、測試、擴充元件等等的來裝備
env
；
那些也可以在之後新增，而我們不會在本書中進一步涵蓋它們。
在接下來章節的範例中，我們假設
env
單純只以
loader=jinja2.
FileSystemLoader('/path/to/templates')
來實體化，而沒有進一步強化 ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.