improved documentation

doc/examples/basic_json__value_ptr.cpp

+#include <json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    // create a JSON object with different entry types
+    json j =
+    {
+        {"integer", 1},
+        {"floating", 42.23},
+        {"string", "hello world"},
+        {"boolean", true},
+        {"object", {{"key1", 1}, {"key2", 2}}},
+        {"array", {1, 2, 3}}
+    };
+
+    // access existing values
+    int v_integer = j.value("/integer"_json_pointer, 0);
+    double v_floating = j.value("/floating"_json_pointer, 47.11);
+
+    // access nonexisting values and rely on default value
+    std::string v_string = j.value("/nonexisting"_json_pointer, "oops");
+    bool v_boolean = j.value("/nonexisting"_json_pointer, false);
+
+    // output values
+    std::cout << std::boolalpha << v_integer << " " << v_floating
+              << " " << v_string << " " << v_boolean << "\n";
+}

doc/examples/basic_json__value_ptr.link

+<a target="_blank" href="http://melpon.org/wandbox/permlink/K4L4D6nibuGXbjfd"><b>online</b></a>
\ No newline at end of file

doc/examples/basic_json__value_ptr.output

+1 42.23 oops false

src/json.hpp

@@ -974,7 +974,9 @@ class basic_json
 
     @since version 1.0.0
     */
-    using parser_callback_t = std::function<bool(int depth, parse_event_t event, basic_json& parsed)>;
+    using parser_callback_t = std::function<bool(int depth,
+                              parse_event_t event,
+                              basic_json& parsed)>;
 
 
     //////////////////
@@ -3716,6 +3718,21 @@ class basic_json
     /*!
     @brief access specified object element via JSON Pointer with default value
 
+    Returns either a copy of an object's element at the specified key @a key
+    or a given default value if no element with key @a key exists.
+
+    The function is basically equivalent to executing
+    @code {.cpp}
+    try {
+        return at(ptr);
+    } catch(std::out_of_range) {
+        return default_value;
+    }
+    @endcode
+
+    @note Unlike @ref at(const json_pointer&), this function does not throw
+    if the given key @a key was not found.
+
     @param[in] ptr  a JSON pointer to the element to access
     @param[in] default_value  the value to return if @a ptr found no value
 
@@ -3724,6 +3741,19 @@ class basic_json
     JSON arrays. Note the type of the expected value at @a key and the default
     value @a default_value must be compatible.
 
+    @return copy of the element at key @a key or @a default_value if @a key
+    is not found
+
+    @throw std::domain_error if JSON is not an object; example: `"cannot use
+    value() with null"`
+
+    @complexity Logarithmic in the size of the container.
+
+    @liveexample{The example below shows how object elements can be queried
+    with a default value.,basic_json__value_ptr}
+
+    @sa @ref operator[](const json_ptr&) for unchecked access by reference
+
     @since version 2.0.2
     */
     template <class ValueType, typename

src/json.hpp.re2c

@@ -974,7 +974,9 @@ class basic_json
 
     @since version 1.0.0
     */
-    using parser_callback_t = std::function<bool(int depth, parse_event_t event, basic_json& parsed)>;
+    using parser_callback_t = std::function<bool(int depth,
+                              parse_event_t event,
+                              basic_json& parsed)>;
 
 
     //////////////////
@@ -3716,6 +3718,21 @@ class basic_json
     /*!
     @brief access specified object element via JSON Pointer with default value
 
+    Returns either a copy of an object's element at the specified key @a key
+    or a given default value if no element with key @a key exists.
+
+    The function is basically equivalent to executing
+    @code {.cpp}
+    try {
+        return at(ptr);
+    } catch(std::out_of_range) {
+        return default_value;
+    }
+    @endcode
+
+    @note Unlike @ref at(const json_pointer&), this function does not throw
+    if the given key @a key was not found.
+
     @param[in] ptr  a JSON pointer to the element to access
     @param[in] default_value  the value to return if @a ptr found no value
 
@@ -3724,6 +3741,19 @@ class basic_json
     JSON arrays. Note the type of the expected value at @a key and the default
     value @a default_value must be compatible.
 
+    @return copy of the element at key @a key or @a default_value if @a key
+    is not found
+
+    @throw std::domain_error if JSON is not an object; example: `"cannot use
+    value() with null"`
+
+    @complexity Logarithmic in the size of the container.
+
+    @liveexample{The example below shows how object elements can be queried
+    with a default value.,basic_json__value_ptr}
+
+    @sa @ref operator[](const json_ptr&) for unchecked access by reference
+
     @since version 2.0.2
     */
     template <class ValueType, typename