Merge pull request #3657 from ethereum/codingStyle

Use coding style.

2 files changed, 264 insertions, 2 deletions

diff --git a/CODING_STYLE.md b/CODING_STYLE.md
new file mode 100644
index 00000000..2cc9ac70
--- /dev/null
+++ b/CODING_STYLE.md
@@ -0,0 +1,262 @@
+0. Formatting
+
+GOLDEN RULE: Follow the style of the existing code when you make changes.
+
+a. Use tabs for leading indentation
+- tab stops are every 4 characters (only relevant for line length).
+- One indentation level -> exactly one byte (i.e. a tab character) in the source file.
+b. Line widths:
+- Lines should be at most 99 characters wide to make diff views readable and reduce merge conflicts.
+- Lines of comments should be formatted according to ease of viewing, but simplicity is to be preferred over beauty.
+c. Single-statement blocks should not have braces, unless required for clarity.
+d. Never place condition bodies on same line as condition.
+e. Space between keyword and opening parenthesis, but not following opening parenthesis or before final parenthesis.
+f. No spaces for unary operators, `->` or `.`.
+g. No space before ':' but one after it, except in the ternary operator: one on both sides.
+h. Add spaces around all other operators.
+i. Braces, when used, always have their own lines and are at same indentation level as "parent" scope.
+j. If lines are broken, a list of elements enclosed with parentheses (of any kind) and separated by a
+   separator (of any kind) are formatted such that there is exactly one element per line, followed by
+   the separator, the opening parenthesis is on the first line, followed by a line break and the closing
+   parenthesis is on a line of its own (unindented). See example below.
+
+(WRONG)
+if( a==b[ i ] ) { printf ("Hello\n"); }
+foo->bar(someLongVariableName,
+         anotherLongVariableName,
+         anotherLongVariableName,
+         anotherLongVariableName,
+         anotherLongVariableName);
+cout << "some very long string that contains completely irrelevant text that talks about this and that and contains the words \"lorem\" and \"ipsum\"" << endl;
+
+(RIGHT)
+if (a == b[i])
+    printf("Hello\n");	// NOTE spaces used instead of tab here for clarity - first byte should be '\t'.
+foo->bar(
+    someLongVariableName,
+    anotherLongVariableName,
+    anotherLongVariableName,
+    anotherLongVariableName,
+    anotherLongVariableName
+);
+cout <<
+    "some very long string that contains completely irrelevant " <<
+    "text that talks about this and that and contains the words " <<
+    "\"lorem\" and \"ipsum\"" <<
+    endl;
+
+
+
+1. Namespaces;
+
+a. No "using namespace" declarations in header files.
+b. All symbols should be declared in a namespace except for final applications.
+c. Use anonymous namespaces for helpers whose scope is a cpp file only.
+d. Preprocessor symbols should be prefixed with the namespace in all-caps and an underscore.
+
+(WRONG)
+#include <cassert>
+using namespace std;
+tuple<float, float> meanAndSigma(vector<float> const& _v);
+
+(CORRECT)
+#include <cassert>
+std::tuple<float, float> meanAndSigma(std::vector<float> const& _v);
+
+
+
+2. Preprocessor;
+
+a. File comment is always at top, and includes:
+- Copyright.
+- License (e.g. see COPYING).
+b. Never use #ifdef/#define/#endif file guards. Prefer #pragma once as first line below file comment.
+c. Prefer static const variable to value macros.
+d. Prefer inline constexpr functions to function macros.
+e. Split complex macro on multiple lines with '\'.
+
+
+
+3. Capitalization;
+
+GOLDEN RULE: Preprocessor: ALL_CAPS; C++: camelCase.
+
+a. Use camelCase for splitting words in names, except where obviously extending STL/boost functionality in which case follow those naming conventions.
+b. The following entities' first alpha is upper case:
+- Type names.
+- Template parameters.
+- Enum members.
+- static const variables that form an external API.
+c. All preprocessor symbols (macros, macro arguments) in full uppercase with underscore word separation.
+
+
+All other entities' first alpha is lower case.
+
+
+
+4. Variable prefixes:
+
+a. Leading underscore "_" to parameter names.
+- Exception: "o_parameterName" when it is used exclusively for output. See 6(f).
+- Exception: "io_parameterName" when it is used for both input and output. See 6(f).
+b. Leading "g_" to global (non-const) variables.
+c. Leading "s_" to static (non-const, non-global) variables.
+
+
+
+5. Assertions:
+
+- use `solAssert` and `solUnimplementedAssert` generously to check assumptions
+  that span across different parts of the code base, for example before dereferencing
+  a pointer.
+
+
+6. Declarations:
+
+a. {Typename} + {qualifiers} + {name}.
+b. Only one per line.
+c. Associate */& with type, not variable (at ends with parser, but more readable, and safe if in conjunction with (b)).
+d. Favour declarations close to use; don't habitually declare at top of scope ala C.
+e. Pass non-trivial parameters as const reference, unless the data is to be copied into the function, then either pass by const reference or by value and use std::move.
+f. If a function returns multiple values, use std::tuple (std::pair acceptable) or better introduce a struct type. Do not use */& arguments.
+g. Use parameters of pointer type only if ``nullptr`` is a valid argument, use references otherwise. Often, ``boost::optional`` is better suited than a raw pointer.
+h. Never use a macro where adequate non-preprocessor C++ can be written.
+i. Only use ``auto`` if the type is very long and rather irrelevant.
+j. Do not pass bools: prefer enumerations instead.
+k. Prefer enum class to straight enum.
+l. Always initialize POD variables, even if their value is overwritten later.
+
+
+(WRONG)
+const double d = 0;
+int i, j;
+char *s;
+float meanAndSigma(std::vector<float> _v, float* _sigma, bool _approximate);
+Derived* x(dynamic_cast<Derived*>(base));
+for (map<ComplexTypeOne, ComplexTypeTwo>::iterator i = l.begin(); i != l.end(); ++l) {}
+
+
+(CORRECT)
+enum class Accuracy
+{
+	Approximate,
+	Exact
+};
+struct MeanSigma
+{
+	float mean;
+	float standardDeviation;
+};
+double const d = 0;
+int i;
+int j;
+char* s;
+MeanAndSigma ms meanAndSigma(std::vector<float> const& _v, Accuracy _a);
+Derived* x = dynamic_cast<Derived*>(base);
+for (auto i = x->begin(); i != x->end(); ++i) {}
+
+
+7. Structs & classes
+
+a. Structs to be used when all members public and no virtual functions.
+- In this case, members should be named naturally and not prefixed with 'm_'
+b. Classes to be used in all other circumstances.
+
+
+
+8. Members:
+
+a. One member per line only.
+b. Private, non-static, non-const fields prefixed with m_.
+c. Avoid public fields, except in structs.
+d. Use override, final and const as much as possible.
+e. No implementations with the class declaration, except:
+- template or force-inline method (though prefer implementation at bottom of header file).
+- one-line implementation (in which case include it in same line as declaration).
+f. For a property 'foo'
+- Member: m_foo;
+- Getter: foo() [ also: for booleans, isFoo() ];
+- Setter: setFoo();
+
+
+
+9. Naming
+
+a. Avoid unpronouncable names
+b. Names should be shortened only if they are extremely common, but shortening should be generally avoided
+c. Avoid prefixes of initials (e.g. do not use IMyInterface, CMyImplementation)
+c. Find short, memorable & (at least semi-) descriptive names for commonly used classes or name-fragments.
+- A dictionary and thesaurus are your friends.
+- Spell correctly.
+- Think carefully about the class's purpose.
+- Imagine it as an isolated component to try to decontextualise it when considering its name.
+- Don't be trapped into naming it (purely) in terms of its implementation.
+
+
+
+10. Type-definitions
+
+a. Prefer 'using' to 'typedef'. e.g. using ints = std::vector<int>; rather than typedef std::vector<int> ints;
+b. Generally avoid shortening a standard form that already includes all important information:
+- e.g. stick to shared_ptr<X> rather than shortening to ptr<X>.
+c. Where there are exceptions to this (due to excessive use and clear meaning), note the change prominently and use it consistently.
+- e.g. using Guard = std::lock_guard<std::mutex>; ///< Guard is used throughout the codebase since it is clear in meaning and used commonly. 
+d. In general expressions should be roughly as important/semantically meaningful as the space they occupy.
+e. Avoid introducing aliases for types unless they are very complicated. Consider the number of items a brain can keep track of at the same time.
+
+
+
+11. Commenting
+
+a. Comments should be doxygen-compilable, using @notation rather than \notation.
+b. Document the interface, not the implementation.
+- Documentation should be able to remain completely unchanged, even if the method is reimplemented.
+- Comment in terms of the method properties and intended alteration to class state (or what aspects of the state it reports).
+- Be careful to scrutinise documentation that extends only to intended purpose and usage.
+- Reject documentation that is simply an English transaction of the implementation.
+c. Avoid in-code comments. Instead, try to extract blocks of functionality into functions. This often already eliminates the need for an in-code comment.
+
+
+12. Include Headers
+
+Includes should go in increasing order of generality (libsolidity -> libevmasm -> libdevcore -> boost -> STL).
+The corresponding .h file should be the first include in the respective .cpp file.
+Insert empty lines between blocks of include files.
+
+Example:
+
+```
+#include <libsolidity/codegen/ExpressionCompiler.h>
+
+#include <libsolidity/ast/AST.h>
+#include <libsolidity/codegen/CompilerContext.h>
+#include <libsolidity/codegen/CompilerUtils.h>
+#include <libsolidity/codegen/LValue.h>
+
+#include <libevmasm/GasMeter.h>
+
+#include <libdevcore/Common.h>
+#include <libdevcore/SHA3.h>
+
+#include <boost/range/adaptor/reversed.hpp>
+#include <boost/algorithm/string/replace.hpp>
+
+#include <utility>
+#include <numeric>
+```
+
+See http://stackoverflow.com/questions/614302/c-header-order/614333#614333 for the reason: this makes it easier to find missing includes in header files.
+
+
+13. Recommended reading
+
+Herb Sutter and Bjarne Stroustrup
+- "C++ Core Guidelines" (https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md)
+
+Herb Sutter and Andrei Alexandrescu
+- "C++ Coding Standards: 101 Rules, Guidelines, and Best Practices"
+
+Scott Meyers
+- "Effective C++: 55 Specific Ways to Improve Your Programs and Designs (3rd Edition)"
+- "More Effective C++: 35 New Ways to Improve Your Programs and Designs"
+- "Effective Modern C++: 42 Specific Ways to Improve Your Use of C++11 and C++14"
diff --git a/docs/contributing.rst b/docs/contributing.rst
index 1bcaed7c..7c199d53 100644
--- a/docs/contributing.rst
+++ b/docs/contributing.rst
@@ -55,8 +55,8 @@ However, if you are making a larger change, please consult with the `Solidity De
 focused on compiler and language development instead of language use) first.
 
 
-Finally, please make sure you respect the `coding standards
-<https://raw.githubusercontent.com/ethereum/cpp-ethereum/develop/CodingStandards.txt>`_
+Finally, please make sure you respect the `coding style
+<https://raw.githubusercontent.com/ethereum/solidity/develop/CODING_STYLE.md>`_
 for this project. Also, even though we do CI testing, please test your code and
 ensure that it builds locally before submitting a pull request.