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Foreword
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========
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Read this before you get started with Flask. This hopefully answers some
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questions about the intention of the project, what it aims at and when you
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should or should not be using it.
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What does Micro Mean?
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---------------------
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The micro in microframework for me means on the one hand being small in
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size, complexity but on the other hand also that the complexity of the
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applications that are written with these frameworks do not exceed a
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certain size. A microframework like Flask sacrifices a few things in
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order to be approachable and to be as concise as possible.
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For example Flask uses thread local objects internally so that you don't
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have to pass objects around from function to function within a request in
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order to stay threadsafe. While this is a really easy approach and saves
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you a lot of time, it also does not scale well to large applications.
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It's especially painful for more complex unittests and when you suddenly
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have to deal with code being executed outside of the context of a request
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(for example if you have cronjobs).
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Flask provides some tools to deal with the downsides of this approach but
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the core problem of this approach obviously stays. It is also based on
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convention over configuration which means that a lot of things are
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preconfigured in Flask and will work well for smaller applications but not
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so much for larger ones (where and how it looks for templates, static
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files etc.)
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But don't worry if your application suddenly grows larger than it was
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initially and you're afraid Flask might not grow with it. Even with
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larger frameworks you sooner or later will find out that you need
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something the framework just cannot do for you without modification.
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If you are ever in that situation, check out the :ref:`becomingbig`
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chapter.
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A Framework and An Example
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--------------------------
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Flask is not only a microframework, it is also an example. Based on
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Flask, there will be a series of blog posts that explain how to create a
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framework. Flask itself is just one way to implement a framework on top
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of existing libraries. Unlike many other microframeworks Flask does not
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try to implement anything on its own, it reuses existing code.
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Target Audience
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---------------
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Is Flask for you? Is your application small-ish (less than 4000 lines of
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Python code) and does not depend on too complex database structures, Flask
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is the Framework for you. It was designed from the ground up to be easy
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to use, based on established principles, good intentions and on top of two
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established libraries in widespread usage.
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Flask serves two purposes: it's an example of how to create a minimal and
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opinionated framework on top of Werkzeug to show how this can be done, and
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to provide people with a simple tool to prototype larger applications or
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to implement small and medium sized applications.
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If you suddenly discover that your application grows larger than
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originally intended, head over to the :ref:`becomingbig` section to see
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some possible solutions for larger applications.
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Satisfied? Then head over to the :ref:`installation`.
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