components/jansson/doc/html/_sources/upgrading.txt
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+.. highlight:: c
+
+******************
+Upgrading from 1.x
+******************
+
+This chapter lists the backwards incompatible changes introduced in
+Jansson 2.0, and the steps that are needed for upgrading your code.
+
+**The incompatibilities are not dramatic.** The biggest change is that
+all decoding functions now require and extra parameter. Most programs
+can be modified to work with 2.0 by adding a ``0`` as the second
+parameter to all calls of :func:`json_loads()`, :func:`json_loadf()`
+and :func:`json_load_file()`.
+
+
+Compatibility
+=============
+
+Jansson 2.0 is backwards incompatible with the Jansson 1.x releases.
+It is ABI incompatible, i.e. all programs dynamically linking to the
+Jansson library need to be recompiled. It's also API incompatible,
+i.e. the source code of programs using Jansson 1.x may need
+modifications to make them compile against Jansson 2.0.
+
+All the 2.x releases are guaranteed to be backwards compatible for
+both ABI and API, so no recompilation or source changes are needed
+when upgrading from 2.x to 2.y.
+
+
+List of Incompatible Changes
+============================
+
+**Decoding flags**
+    For future needs, a ``flags`` parameter was added as the second
+    parameter to all decoding functions, i.e. :func:`json_loads()`,
+    :func:`json_loadf()` and :func:`json_load_file()`. All calls to
+    these functions need to be changed by adding a ``0`` as the second
+    argument. For example::
+
+        /* old code */
+        json_loads(input, &error);
+
+        /* new code */
+        json_loads(input, 0, &error);
+
+
+**Underlying type of JSON integers**
+    The underlying C type of JSON integers has been changed from
+    :type:`int` to the widest available signed integer type, i.e.
+    :type:`long long` or :type:`long`, depending on whether
+    :type:`long long` is supported on your system or not. This makes
+    the whole 64-bit integer range available on most modern systems.
+
+    ``jansson.h`` has a typedef :type:`json_int_t` to the underlying
+    integer type. :type:`int` should still be used in most cases when
+    dealing with smallish JSON integers, as the compiler handles
+    implicit type coercion. Only when the full 64-bit range is needed,
+    :type:`json_int_t` should be explicitly used.
+
+
+**Maximum encoder indentation depth**
+    The maximum argument of the ``JSON_INDENT()`` macro has been
+    changed from 255 to 31, to free up bits from the ``flags``
+    parameter of :func:`json_dumps()`, :func:`json_dumpf()` and
+    :func:`json_dump_file()`. If your code uses a bigger indentation
+    than 31, it needs to be changed.
+
+
+**Unsigned integers in API functions**
+    Version 2.0 unifies unsigned integer usage in the API. All uses of
+    :type:`unsigned int` and :type:`unsigned long` have been replaced
+    with :type:`size_t`. This includes flags, container sizes, etc.
+    This should not require source code changes, as both
+    :type:`unsigned int` and :type:`unsigned long` are usually
+    compatible with :type:`size_t`.