better name - mu - Soul of a tiny new machine. More thorough tests → More comprehensible and rewrite-friendly software → More resilient society.

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author	Kartik K. Agaram <vc@akkartik.com>	2021-06-11 20:10:17 -0700
committer	Kartik K. Agaram <vc@akkartik.com>	2021-06-11 20:11:16 -0700
commit	31918612428c82652934be7b2e3ffc347e19ff2c (patch)
tree	93b5559905c037ed809790a616da5a54383c3078 /html/412render-float-decimal.mu.html
parent	ef29fcdc9170dec59c1b38f01e72cb8ad8c69550 (diff)
download	mu-31918612428c82652934be7b2e3ffc347e19ff2c.tar.gz

better name

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//: The goal of this skeleton is to make programs more easy to understand and //: more malleable, easy to rewrite in radical ways without accidentally //: breaking some corner case. Tests further both goals. They help //: understandability by letting one make small changes and get feedback. What //: if I wrote this line like so? What if I removed this function call, is it //: really necessary? Just try it, see if the tests pass. Want to explore //: rewriting this bit in this way? Tests put many refactorings on a firmer //: footing. //: //: But the usual way we write tests seems incomplete. Refactorings tend to //: work in the small, but don't help with changes to function boundaries. If //: you want to extract a new function you have to manually test-drive it to //: create tests for it. If you want to inline a function its tests are no //: longer valid. In both cases you end up having to reorganize code as well as //: tests, an error-prone activity. //: //: This file tries to fix this problem by supporting domain-driven testing //: We try to focus on the domain of inputs the program should work on. All //: tests invoke the program in a single way: by calling run() with different //: inputs. The program operates on the input and logs _facts_ it deduces to a //: trace: //: trace("label") << "fact 1: " << val; //: //: The tests check for facts: //: :(scenario foo) //: 34 # call run() with this input //: +label: fact 1: 34 # trace should have logged this at the end //: -label: fact 1: 35 # trace should never contain such a line //: //: Since we never call anything but the run() function directly, we never have //: to rewrite the tests when we reorganize the internals of the program. We //: just have to make sure our rewrite deduces the same facts about the domain, //: and that's something we're going to have to do anyway. //: //: To avoid the combinatorial explosion of integration tests, we organize the //: program into different layers, and each fact is logged to the trace with a //: specific label. Individual tests can focus on specific labels. In essence, //: validating the facts logged with a specific label is identical to calling //: some internal subsystem. //: //: Traces interact salubriously with layers. Thanks to our ordering //: directives, each layer can contain its own tests. They may rely on other //: layers, but when a test fails its usually due to breakage in the same //: layer. When multiple tests fail, it's usually useful to debug the very //: first test to fail. This is in contrast with the traditional approach, //: where changes can cause breakages in faraway subsystems, and picking the //: right test to debug can be an important skill to pick up. //: //: To build robust tests, trace facts about your domain rather than details of //: how you computed them. //: //: More details: http://akkartik.name/blog/tracing-tests //: //: --- //: //: Between layers and domain-driven testing, programming starts to look like a //: fundamentally different activity. Instead of a) superficial, b) local rules //: on c) code [like http://blog.bbv.ch/2013/06/05/clean-code-cheat-sheet], //: we allow programmers to engage with the a) deep, b) global structure of the //: c) domain. If you can systematically track discontinuities in the domain //: you don't care if the code used gotos as long as it passed the tests. If //: tests become more robust to run it becomes easier to try out radically //: different implementations for the same program. If code is super-easy to //: rewrite, it becomes less important what indentation style it uses, or that //: the objects are appropriately encapsulated, or that the functions are //: referentially transparent. //: //: Instead of plumbing, programming becomes building and gradually refining a //: map of the environment the program must operate under. Whether a program is //: 'correct' at a given point in time is a red herring; what matters is //: avoiding regression by monotonically nailing down the more 'eventful' parts //: of the terrain. It helps readers new and old and rewards curiosity to //: organize large programs in self-similar hiearchies of example scenarios //: colocated with the code that makes them work. //: //: "Programming properly should be regarded as an activity by which //: programmers form a mental model, rather than as production of a program." //: -- Peter Naur (http://alistair.cockburn.us/ASD+book+extract%3A+%22Naur,+Ehn,+Musashi%22) :(before "int main") // End Tracing // hack to ensure most code in this layer comes before anything else :(before "End Tracing") bool Hide_warnings = false; :(before "End Setup") //? cerr << "AAA setup\n"; //? 2 Hide_warnings = false; :(before "End Types") struct trace_line { int depth; // optional field just to help browse traces later string label; string contents; trace_line(string l, string c) :depth(0), label(l), contents(c) {} trace_line(int d, string l, string c) :depth(d), label(l), contents(c) {} }; :(before "End Tracing") struct trace_stream { vector<trace_line> past_lines; // accumulator for current line ostringstream* curr_stream; string curr_layer; int curr_depth; string dump_layer; string collect_layer; // if set, ignore all other layers ofstream null_stream; // never opens a file, so writes silently fail trace_stream() :curr_stream(NULL), curr_depth(0) {} ~trace_stream() { if (curr_stream) delete curr_stream; } ostream& stream(string layer) { return stream(0, layer); } ostream& stream(int depth, string layer) { if (!collect_layer.empty() && layer != collect_layer) return null_stream; newline(); curr_stream = new ostringstream; curr_layer = layer; curr_depth = depth; return *curr_stream; } // be sure to call this before messing with curr_stream or curr_layer void newline() { if (!curr_stream) return; string curr_contents = curr_stream->str(); past_lines.push_back(trace_line(curr_depth, trim(curr_layer), curr_contents)); // preserve indent in contents if (curr_layer == dump_layer || curr_layer == "dump" || dump_layer == "all" || (!Hide_warnings && curr_layer == "warn")) //? if (dump_layer == "all" && (Current_routine->id == 3 || curr_layer == "schedule")) //? 1 cerr << curr_layer << ": " << curr_contents << '\n'; delete curr_stream; curr_stream = NULL; curr_layer.clear(); curr_depth = 0; } // Useful for debugging. string readable_contents(string layer) { // missing layer = everything newline(); ostringstream output; layer = trim(layer); for (vector<trace_line>::iterator p = past_lines.begin(); p != past_lines.end(); ++p) if (layer.empty() || layer == p->label) { if (p->depth) output << std::setw(4) << p->depth << ' '; output << p->label << ": " << p->contents << '\n'; } return output.str(); } }; trace_stream* Trace_stream = NULL; // Top-level helper. IMPORTANT: can't nest. #define trace(...) !Trace_stream ? cerr /*print nothing*/ : Trace_stream->stream(__VA_ARGS__) // Warnings should go straight to cerr by default since calls to trace() have // some unfriendly constraints (they delay printing, they can't nest) #define raise ((!Trace_stream || !Hide_warnings) ? (tb_shutdown(),cerr) /*do print*/ : Trace_stream->stream("warn")) // A separate helper for debugging. We should only trace domain-specific // facts. For everything else use log. #define xlog if (false) log // To turn on logging replace 'xlog' with 'log'. #define log cerr :(before "End Types") // raise << die exits after printing -- unless Hide_warnings is set. struct die {}; :(before "End Tracing") ostream& operator<<(ostream& os, unused die) { if (Hide_warnings) return os; tb_shutdown(); os << "dying"; if (Trace_stream) Trace_stream->newline(); exit(1); } #define CLEAR_TRACE delete Trace_stream, Trace_stream = new trace_stream; #define DUMP(layer) if (Trace_stream) cerr << Trace_stream->readable_contents(layer); // All scenarios save their traces in the repo, just like code. This gives // future readers more meat when they try to make sense of a new project. static string Trace_dir = ".traces/"; string Trace_file; // Trace_stream is a resource, lease_tracer uses RAII to manage it. struct lease_tracer { lease_tracer() { Trace_stream = new trace_stream; } ~lease_tracer() { //? cerr << "write to file? " << Trace_file << "$\n"; //? 2 if (!Trace_file.empty()) { //? cerr << "writing\n"; //? 2 ofstream fout((Trace_dir+Trace_file).c_str()); fout << Trace_stream->readable_contents(""); fout.close(); } delete Trace_stream, Trace_stream = NULL, Trace_file = ""; } }; #define START_TRACING_UNTIL_END_OF_SCOPE lease_tracer leased_tracer; :(before "End Test Setup") START_TRACING_UNTIL_END_OF_SCOPE //? Trace_stream->dump_layer = "all"; //? 1 #define CHECK_TRACE_CONTENTS(...) check_trace_contents(__FUNCTION__, __FILE__, __LINE__, __VA_ARGS__) :(before "End Tracing") bool check_trace_contents(string FUNCTION, string FILE, int LINE, string expected) { // missing layer == anywhere vector<string> expected_lines = split(expected, ""); long long int curr_expected_line = 0; while (curr_expected_line < SIZE(expected_lines) && expected_lines.at(curr_expected_line).empty()) ++curr_expected_line; if (curr_expected_line == SIZE(expected_lines)) return true; Trace_stream->newline(); string layer, contents; split_layer_contents(expected_lines.at(curr_expected_line), &layer, &contents); for (vector<trace_line>::iterator p = Trace_stream->past_lines.begin(); p != Trace_stream->past_lines.end(); ++p) { //? cerr << "AAA " << layer << ' ' << p->label << '\n'; //? 1 if (layer != p->label) continue; //? cerr << "BBB ^" << contents << "$ ^" << p->contents << "$\n"; //? 1 if (contents != trim(p->contents)) continue; //? cerr << "CCC\n"; //? 1 ++curr_expected_line; while (curr_expected_line < SIZE(expected_lines) && expected_lines.at(curr_expected_line).empty()) ++curr_expected_line; if (curr_expected_line == SIZE(expected_lines)) return true; split_layer_contents(expected_lines.at(curr_expected_line), &layer, &contents); } ++Num_failures; cerr << "\nF - " << FUNCTION << "(" << FILE << ":" << LINE << "): missing [" << contents << "] in trace:\n"; DUMP(layer); //? exit(0); //? 1 Passed = false; return false; } void split_layer_contents(const string& s, string* layer, string* contents) { static const string delim(": "); size_t pos = s.find(delim); if (pos == string::npos) { *layer = ""; *contents = trim(s); } else { *layer = trim(s.substr(0, pos)); *contents = trim(s.substr(pos+SIZE(delim))); } } int trace_count(string layer) { return trace_count(layer, ""); } int trace_count(string layer, string line) { Trace_stream->newline(); long result = 0; for (vector<trace_line>::iterator p = Trace_stream->past_lines.begin(); p != Trace_stream->past_lines.end(); ++p) { if (layer == p->label) { //? cerr << "a: " << line << "$\n"; //? 1 //? cerr << "b: " << trim(p->contents) << "$\n"; //? 1 if (line == "" || line == trim(p->contents)) ++result; } } return result; } #define CHECK_TRACE_WARNS() CHECK(trace_count("warn") > 0) #define CHECK_TRACE_DOESNT_WARN() \ if (trace_count("warn") > 0) { \ ++Num_failures; \ cerr << "\nF - " << __FUNCTION__ << "(" << __FILE__ << ":" << __LINE__ << "): unexpected warnings\n"; \ DUMP("warn"); \ Passed = false; \ return; \ } bool trace_doesnt_contain(string layer, string line) { return trace_count(layer, line) == 0; } bool trace_doesnt_contain(string expected) { vector<string> tmp = split(expected, ": "); return trace_doesnt_contain(tmp.at(0), tmp.at(1)); } #define CHECK_TRACE_DOESNT_CONTAIN(...) CHECK(trace_doesnt_contain(__VA_ARGS__)) vector<string> split(string s, string delim) { vector<string> result; size_t begin=0, end=s.find(delim); while (true) { if (end == string::npos) { result.push_back(string(s, begin, string::npos)); break; } result.push_back(string(s, begin, end-begin)); begin = SIZE(end+delim); end = s.find(delim, begin); } return result; } string trim(const string& s) { string::const_iterator first = s.begin(); while (first != s.end() && isspace(*first)) ++first; if (first == s.end()) return ""; string::const_iterator last = --s.end(); while (last != s.begin() && isspace(*last)) --last; ++last; return string(first, last); } :(before "End Includes") #include<vector> using std::vector; #include<list> using std::list; #include<map> using std::map; #include<set> using std::set; #include<algorithm> #include<iostream> using std::istream; using std::ostream; using std::cin; using std::cout; using std::cerr; #include<iomanip> #include<sstream> using std::istringstream; using std::ostringstream; #include<fstream> using std::ifstream; using std::ofstream; #include"termbox/termbox.h" #define unused __attribute__((unused)) :(before "End Globals") //: In future layers we'll use the depth field as follows: //: //: Mu 'applications' will be able to use depths 1-99 as they like. //: Depth 100 will be for scheduling (more on that later). const int Scheduling_depth = 100; //: Primitive statements will occupy 101-9998 const int Initial_callstack_depth = 101; const int Max_callstack_depth = 9998; //: (ignore this until the call layer) :(before "End Globals") int Callstack_depth = 0; :(before "End Setup") Callstack_depth = 0; //: Finally, details of primitive mu statements will occupy depth 9999 (more on that later as well) :(before "End Globals") const int Primitive_recipe_depth = 9999; //: //: This framework should help us hide some details at each level, mixing //: static ideas like layers with the dynamic notion of call-stack depth.


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