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On Saturday, 13 January 2024 at 06:46:54 UTC, Walter Bright wrote:
>So you agree it is not simpler :-)
Let’s compare them side by side.
// DIP1027 + Sliding Template Arguments
// core.interpolation:
enum FormatString: string;
// Or, alternatively:
// struct FormatString { string s; }
// User-library code:
string generateSql(FormatString fmt) {
import std.conv: text;
string sql;
int number;
for (size_t i = 0; i < fmt.length; ++i) {
char c = fmt[i];
if (c == '%' && i + 1 < fmt.length && fmt[i + 1] == 's') {
sql ~= text('?', ++number);
++i;
} else if (c == '%' && i + 1 < fmt.length && fmt[i + 1] == '%')
++i;
else
sql ~= c;
}
return sql;
}
auto execi(FormatString fmt, Args...)(Sqlite db, Args args) {
enum query = generateSql(fmt); // CTFE.
auto statement = Statement(db, query);
static foreach (i, arg; args)
statement.bind(i + 1, arg);
return statement.execute();
}
// User code:
db.execi(i"SELECT * FROM items WHERE id = $desiredId");
// Desugars to:
db.execi(cast(FormatString)"SELECT * FROM items WHERE id = %s", desiredId);
Vs.
// Steven's proposal + Sliding Template Arguments
// core.interpolation:
struct Interpolation {
immutable(string)[ ] parts;
}
// User-library code:
string generateSql(Interpolation interp) {
import std.conv: text;
string sql;
foreach (i, part; interp.parts)
sql ~= i & 0x1 ? text('?', i / 2 + 1) : part;
return sql;
}
// No changes here.
auto execi(Interpolation interp, Args...)(Sqlite db, Args args) {
enum query = generateSql(interp); // CTFE.
auto statement = Statement(db, query);
static foreach (i, arg; args)
statement.bind(i + 1, arg);
return statement.execute();
}
// User code:
db.execi(i"SELECT * FROM items WHERE id = $desiredId");
// Desugars to:
db.execi(Interpolation(["SELECT * FROM items WHERE id = ", "desiredId", ""]), desiredId);
Which one is simpler?
(Note that neither of them will actually work due to the fact FormatString/Interpolation is not the first argument, but that’s not the point I’m arguing here.)
